Improve the remaining easily improvable water bodies

For the Gulf of Mexico, note that the original NOAA image was indeed a JPG.

sources.csv

@@ -321,7 +321,7 @@ ug-map-cape_verde.png,,,
 ug-map-caribbean_sea.jpg,?,,
 ug-map-caspian_sea.jpg,?,,
 ug-map-cayman_islands.png,,,
-ug-map-celtic_sea.jpg,https://commons.wikimedia.org/wiki/File:Mappa_an_Mor_Keltek.png,PD,added white line on side
+ug-map-celtic_sea.png,https://commons.wikimedia.org/wiki/File:Mappa_an_Mor_Keltek.png,PD,optimised with optipng
 ug-map-central_african_republic.png,,,
 ug-map-ceuta.png,https://commons.wikimedia.org/wiki/File:Localizaci%C3%B3n_de_Ceuta.svg,CC BY-SA 3.0,"407px PNG, optimised with optipng"
 ug-map-chad.png,,,
@@ -343,7 +343,7 @@ ug-map-czech_republic.png,,,
 ug-map-dead_sea.png,https://commons.wikimedia.org/wiki/File:Dead_Sea_in_its_region_(-mini_map_-rivers)_(zoom_%2B_special_marker).svg,CC BY-SA 3.0,"500px version downloaded, optimised with optipng"
 ug-map-democratic_republic_of_the_congo.png,,,
 ug-map-denmark.png,,,
-ug-map-denmark_strait.jpg,https://commons.wikimedia.org/wiki/File:Denemarkenstraat.PNG,PD,
+ug-map-denmark_strait.png,https://commons.wikimedia.org/wiki/File:Denemarkenstraat.PNG,PD,optimised with optipng
 ug-map-djibouti.png,,,
 ug-map-dominica.png,,,
 ug-map-dominican_republic.png,,,
@@ -387,7 +387,7 @@ ug-map-guinea-bissau.png,,,
 ug-map-guinea.png,,,
 ug-map-gulf_of_california.jpg,?,,
 ug-map-gulf_of_carpentaria.jpg,?,,
-ug-map-gulf_of_mexico.jpg,https://commons.wikimedia.org/wiki/File:Gulf_of_Mexico_places.png,PD,retouched (orange spots removed)
+ug-map-gulf_of_mexico.jpg,https://commons.wikimedia.org/wiki/File:GulfofMexico3D.jpg,PD,question mark added
 ug-map-gulf_of_thailand.jpg,?,,
 ug-map-guyana.png,,,
 ug-map-haiti.png,,,

src/data.csv

@@ -273,10 +273,10 @@ d]f3d/htPe,"Indian Ocean","Indischer Ozean",,,,,,,,,,,,"<img src=""ug-map-indian
 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