Improve some of the maps that have slightly better upstream versions

This probably should be split into smaller, atomic commits, but
ideally the commits should also update sources.csv, which doesn't yet
exist in master. I don't want to continue piling pulls on top of
each other, so I'm just pushing this, in case you (or anybody else)
has some comments.

Arctic, Atlantic and Indian Oceans
Azores
Celtic Sea
Ceuta
Denmark strait
Gulf of Mexico
Melilla
Polynesia

The label-free version of the Pacific Ocean on Wikimedia is, for some
reason huge (98 kB) and playing around with pngout and optipng doesn't
help.

The new sources for the files are:

https://commons.wikimedia.org/wiki/File:Arctic_Ocean.png
https://commons.wikimedia.org/wiki/File:Atlantic_Ocean.png
Indian Ocean: same file but use PNG.
Azores: same file but cropped, converted to PNG and optimised
Celtic Sea: same file but use original PNG (optimised)
Ceuta: same file but use PNG (407px), optimise
Denmark strait: same file but use original PNG (optimised)
https://commons.wikimedia.org/wiki/File:GulfofMexico3D.jpg (note that
the original NOAA image was indeed a JPG) (add question mark)
Melilla: same file but use PNG (407px), optimise
Polynesia: same source but new version; remove circles and labels,
optimise

src/data.csv

@@ -211,8 +211,8 @@ oDGbPPlkzc,"British Virgin Islands","Britische Jungferninseln","Overseas territo
 ogLVp1-2mC,"Turks and Caicos Islands","Turks- und Caicosinseln","Overseas territory of the United Kingdom.","Auch Turks &amp; Caicos. Britisches Überseegebiet.","Cockburn Town","Cockburn Town",,,,,"<img src=""ug-flag-turks_and_caicos_islands.svg"" />",,,"<img src=""ug-map-turks_and_caicos_islands.png"" />","UG::America UG::Caribbean"
 t8K|Gnw[k$,"Cayman Islands","Cayman Islands (Kaimaninseln)","Overseas territory of the United Kingdom.","Überseegebiet des Vereinigten Königreichs.","George Town","George Town",,,"Two-word country name",Zwei-Wort-Ländername,"<img src=""ug-flag-cayman_islands.svg"" />",,,"<img src=""ug-map-cayman_islands.png"" />","UG::America UG::Caribbean"
 cy]sz097{A,Anguilla,Anguilla,"Overseas territory of the United Kingdom.","Britisches Überseegebiet.","The Valley","The Valley",,,,,"<img src=""ug-flag-anguilla.svg"" />",,,"<img src=""ug-map-anguilla.png"" />","UG::America UG::Caribbean"
-"hz,n^64X%i",Azores,"Azoren (Habichtsinseln)","Autonomous region of Portugal.","Autonome Region von Portugal.","Ponta Delgada","Ponta Delgada",,,,,"<img src=""ug-flag-azores.svg"" />",,,"<img src=""ug-map-azores.jpg"" />",UG::Europe
-"rHh8*,y.yc",Ceuta,Ceuta,"Autonomous city of Spain.","Autonome spanische Stadt.",,,,,,,"<img src=""ug-flag-ceuta.png"" />",,,"<img src=""ug-map-ceuta.jpg"" />",UG::Europe
+"hz,n^64X%i",Azores,"Azoren (Habichtsinseln)","Autonomous region of Portugal.","Autonome Region von Portugal.","Ponta Delgada","Ponta Delgada",,,,,"<img src=""ug-flag-azores.svg"" />",,,"<img src=""ug-map-azores.png"" />",UG::Europe
+"rHh8*,y.yc",Ceuta,Ceuta,"Autonomous city of Spain.","Autonome spanische Stadt.",,,,,,,"<img src=""ug-flag-ceuta.png"" />",,,"<img src=""ug-map-ceuta.png"" />",UG::Europe
 k3]]2^DP1R,"Christmas Island",Weihnachtsinsel,"External territory of Australia.","Australisches Außengebiet.","Flying Fish Cove","Flying Fish Cove",,,,,"<img src=""ug-flag-christmas_island.svg"" />",,,"<img src=""ug-map-christmas_island.png"" />","UG::Asia UG::Southeast_Asia"
 mMdbj-!g%k,Curaçao,Curaçao,"Constituent country of the Kingdom of the Netherlands.","Autonomes Land innerhalb des Königreichs der Niederlande.",Willemstad,Willemstad,,,,,"<img src=""ug-flag-curacao.svg"" />","Nauru (single star below yellow band)","Nauru (einzelner Stern unter gelbem Band)","<img src=""ug-map-curacao.png"" />","UG::America UG::Caribbean"
 rNv|0qxR]K,"Easter Island",Osterinsel,"Polynesian island and special territory of Chile.","Polynesische Insel unter Chilenischer Regierung.",,,,,,,"<img src=""ug-flag-easter_island.svg"" />",,,"<img src=""ug-map-easter_island.png"" />",UG::Oceania
@@ -225,7 +225,7 @@ q{72>nP`an,Kiribati,Kiribati,,,"South Tarawa","South Tarawa",,,,,"<img src=""ug-
 k2lcDMRBT~,Macau,Macau,"Special Administrative Region of China.","Sonderverwaltungszone der Volksrepublik China.",,,,,,,"<img src=""ug-flag-macau.svg"" />",,,"<img src=""ug-map-macau.png"" />",UG::Asia
 fKTU=+DKl],Madeira,"Autonome Region Madeira","Autonomous region of Portugal.","Autonome Region von Portugal.",Funchal,Funchal,,,,,"<img src=""ug-flag-madeira.svg"" />",,,"<img src=""ug-map-madeira.png"" />",UG::Europe
 c]uN7LyVsp,"Marshall Islands",Marshallinseln,,,Majuro,Majuro,,,,,"<img src=""ug-flag-marshall_islands.svg"" />",,,"<img src=""ug-map-marshall_islands.png"" />","UG::Oceania UG::Sovereign_State"
-d~3m`ihA*b,Melilla,Melilla,"Autonomous city of Spain","Autonome spanische Stadt.",,,,,,,"<img src=""ug-flag-melilla.png"" />",,,"<img src=""ug-map-melilla.jpg"" />",UG::Europe
+d~3m`ihA*b,Melilla,Melilla,"Autonomous city of Spain","Autonome spanische Stadt.",,,,,,,"<img src=""ug-flag-melilla.png"" />",,,"<img src=""ug-map-melilla.png"" />",UG::Europe
 iq7o#n0juD,Montserrat,Montserrat,"Overseas territory of the United Kingdom.","Überseegebiet des Vereinigten Königreichs.",Brades,Brades,"Eruptions in 1997 destroyed the capital city of Plymouth, making Brades the de facto capital.","Nach einer Reihe von Vulkanausbrüchen wurde die eigentliche Hauptstadt Plymouth 1997 aufgegeben und Brades zur de-facto-Hauptstadt.",,,"<img src=""ug-flag-montserrat.svg"" />",,,"<img src=""ug-map-montserrat.png"" />","UG::America UG::Caribbean"
 t)z=hAWb]&,Nauru,Nauru,,,Yaren,Yaren,"Nauru has no official capital; the Yaren District is the de facto capital.","Nauru hat keine offizielle Hauptstadt; der Yaren District ist der Regierungssitz.",,,"<img src=""ug-flag-nauru.svg"" />","Curaçao (two stars in top-left corner)","Curacao (zwei Sterne in der oberen linken Ecke)","<img src=""ug-map-nauru.png"" />","UG::Oceania UG::Sovereign_State"
 rVjI+Dj-jD,"New Caledonia",Neukaledonien,"Overseas territory of France.","Französische Überseegebiet.",Nouméa,Nouméa,,,,,"<img src=""ug-flag-new_caledonia.svg"" />",,,"<img src=""ug-map-new_caledonia.png"" />",UG::Oceania
@@ -267,16 +267,16 @@ J>%}8KJ$/P,"Southern Ocean","Südlicher Ozean",,,,,,,,,,,,"<img src=""ug-map-sou
 p[VL?c~DNl,"Gulf of Thailand","Golf von Thailand",,,,,,,,,,,,"<img src=""ug-map-gulf_of_thailand.jpg"" />",UG::Oceans+Seas
 a7n-YbtFyN,Micronesia,Mikronesien,"Subregion of Oceania comprising thousands of small islands in the western Pacific Ocean.","Teilregion von Ozeanien bestehend über 2000 tropischen Inseln und Atollen im westlichen Pazifik.",,,,,,,,,,"<img src=""ug-map-micronesia.jpg"" />",UG::Oceania
 dq|xYN)MGZ,"Pacific Ocean","Pazifischer Ozean",,"Auch Pazifik.",,,,,,,,,,"<img src=""ug-map-pacific_ocean.jpg"" />",UG::Oceans+Seas
-l6?c8ziNbK,"Atlantic Ocean","Atlantischer Ozean",,"Auch Atlantik.",,,,,,,,,,"<img src=""ug-map-atlantic_ocean.jpg"" />",UG::Oceans+Seas
-d]f3d/htPe,"Indian Ocean","Indischer Ozean",,,,,,,,,,,,"<img src=""ug-map-indian_ocean.jpg"" />",UG::Oceans+Seas
-"e+b<[K.t,Y","Arctic Ocean","Arktischer Ozean",,"Auch Nordpolarmeer, nördliches Eismeer, Arktische See oder Arktik.",,,,,,,,,,"<img src=""ug-map-arctic_ocean.jpg"" />",UG::Oceans+Seas
+l6?c8ziNbK,"Atlantic Ocean","Atlantischer Ozean",,"Auch Atlantik.",,,,,,,,,,"<img src=""ug-map-atlantic_ocean.png"" />",UG::Oceans+Seas
+d]f3d/htPe,"Indian Ocean","Indischer Ozean",,,,,,,,,,,,"<img src=""ug-map-indian_ocean.png"" />",UG::Oceans+Seas
+"e+b<[K.t,Y","Arctic Ocean","Arktischer Ozean",,"Auch Nordpolarmeer, nördliches Eismeer, Arktische See oder Arktik.",,,,,,,,,,"<img src=""ug-map-arctic_ocean.png"" />",UG::Oceans+Seas
 q;`%:Y|$[Z,"Hudson Bay","Hudson Bay",,,,,,,,,,,,"<img src=""ug-map-hudson_bay.jpg"" />",UG::Oceans+Seas
 bX?b@#G`+b,"Labrador Sea",Labradorsee,,,,,,,,,,,,"<img src=""ug-map-labrador_sea.jpg"" />",UG::Oceans+Seas
 a)/A6i.IDE,"White Sea","Weißes Meer",,"Auch Weißmeer.",,,,,,,,,,"<img src=""ug-map-white_sea.jpg"" />",UG::Oceans+Seas
-c<gAS-(0qJ,"Denmark Strait",Dänemarkstraße,,,,,,,,,,,,"<img src=""ug-map-denmark_strait.jpg"" />",UG::Oceans+Seas
+c<gAS-(0qJ,"Denmark Strait",Dänemarkstraße,,,,,,,,,,,,"<img src=""ug-map-denmark_strait.png"" />",UG::Oceans+Seas
 j1yLgdVnj),"Norwegian Sea","Europäisches Nordmeer",,"Auch Norwegische See/Meer.",,,,,,,,,,"<img src=""ug-map-norwegian_sea.png"" />",UG::Oceans+Seas
 c130}t)$BS,"Baltic Sea",Ostsee,,"Auch Baltisches Meer.",,,,,,,,,,"<img src=""ug-map-baltic_sea.png"" />",UG::Oceans+Seas
-Cc2l|nvbk^,"Celtic Sea","Keltische See",,,,,,,,,,,,"<img src=""ug-map-celtic_sea.jpg"" />",UG::Oceans+Seas
+Cc2l|nvbk^,"Celtic Sea","Keltische See",,,,,,,,,,,,"<img src=""ug-map-celtic_sea.png"" />",UG::Oceans+Seas
 oa;|#Te:Ae,"English Channel",Ärmelkanal,,,,,,,,,,,,"<img src=""ug-map-english_channel.jpg"" />",UG::Oceans+Seas
 w{s0UWM|x@,"Adriatic Sea","Adriatisches Meer",,,,,,,,,,,,"<img src=""ug-map-adriatic_sea.jpg"" />",UG::Oceans+Seas
 FqKy-)oA4;,"Bay of Biscay",Biskaya,,"Auch Golf von Biskaya.",,,,,,,,,,"<img src=""ug-map-bay_of_biscay.jpg"" />",UG::Oceans+Seas
@@ -301,7 +301,7 @@ oU3q~Y:QR;,"Aral Sea",Aralsee,,,,,,,,,,,,"<img src=""ug-map-aral_sea.jpg"" />",U
 KlJJ`wS@RY,"Persian Gulf","Persischer Golf",,"Auch Arabischer Golf.",,,,,,,,,,"<img src=""ug-map-persian_gulf.jpg"" />",UG::Oceans+Seas
 h|7yQG0Wik,"Caribbean Sea","Karibisches Meer",,,,,,,,,,,,"<img src=""ug-map-caribbean_sea.jpg"" />",UG::Oceans+Seas
 :XMC{NXgC,"Gulf of California","Golf von Kalifornien",,,,,,,,,,,,"<img src=""ug-map-gulf_of_california.jpg"" />",UG::Oceans+Seas
-beUci8clxs,Polynesia,Polynesien,"Subregion of Oceania comprising thousands of small islands in the central and southern Pacific Ocean.","Größte Inselregion Ozeaniens.",,,,,,,,,,"<img src=""ug-map-polynesia.jpg"" />",UG::Oceania
+beUci8clxs,Polynesia,Polynesien,"Subregion of Oceania comprising thousands of small islands in the central and southern Pacific Ocean.","Größte Inselregion Ozeaniens.",,,,,,,,,,"<img src=""ug-map-polynesia.png"" />",UG::Oceania
 miE4u575Ez,Melanesia,Melanesien,"Subregion of Oceania, which includes the four countries of&nbsp;Vanuatu, the Solomon Islands, Fiji, and Papua New Guinea.","Teilregion von Ozeanien, zu der die vier Staaten Vanuatu, Salomonen, Fidschi und Papua-Neuguinea gehören.",,,,,,,,,,"<img src=""ug-map-melanesia.jpg"" />",UG::Oceania
 FQfLvMyzbT,Scandinavia,Skandinavien,"Historical and cultural region in Northern Europe, which includes the countries of Denmark, Norway and Sweden, and sometimes Finland and Iceland.","Historische und kulturelle Region in Nordeuropa, die die Länder Dänemark, Norwegen und Schweden und manchmal Finnland und Island umfasst.",,,,,,,,,,"<img src=""ug-map-scandinavia.jpg"" />",UG::Europe
 O[YhHW&F>+,"Sea of Galilee","See Genezareth",,,,,,,,,,,,"<img src=""ug-map-sea_of_galilee.png"" />",UG::Oceans+Seas