PreProc: Use nord10 for all preprocessor-like syntax highlighting

nord10 is the color to use according to the "Colors and Palettes"
documentation. This change simplifies to only defining the syntax
highlighting for PreProc, which (n)vim links the other related highlight
groups by default (see `:help group-name`).

colors/nord.vim

@@ -260,18 +260,16 @@ call s:hi("Conceal", "", "NONE", "", "NONE", "", "")
 call s:hi("Conditional", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Constant", s:nord4_gui, "", "NONE", "", "", "")
 call s:hi("Decorator", s:nord12_gui, "", s:nord12_term, "", "", "")
-call s:hi("Define", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Delimiter", s:nord6_gui, "", s:nord6_term, "", "", "")
 call s:hi("Exception", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Float", s:nord15_gui, "", s:nord15_term, "", "", "")
 call s:hi("Function", s:nord8_gui, "", s:nord8_term, "", "", "")
 call s:hi("Identifier", s:nord4_gui, "", "NONE", "", "NONE", "")
-call s:hi("Include", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Keyword", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Label", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Number", s:nord15_gui, "", s:nord15_term, "", "", "")
 call s:hi("Operator", s:nord9_gui, "", s:nord9_term, "", "NONE", "")
-call s:hi("PreProc", s:nord9_gui, "", s:nord9_term, "", "NONE", "")
+call s:hi("PreProc", s:nord10_gui, "", s:nord10_term, "", "NONE", "")
 call s:hi("Repeat", s:nord9_gui, "", s:nord9_term, "", "", "")
 call s:hi("Special", s:nord4_gui, "", "NONE", "", "", "")
 call s:hi("SpecialChar", s:nord13_gui, "", s:nord13_term, "", "", "")
@@ -285,7 +283,6 @@ call s:hi("Todo", s:nord13_gui, "NONE", s:nord13_term, "NONE", "", "")
 call s:hi("Type", s:nord9_gui, "", s:nord9_term, "", "NONE", "")
 call s:hi("Typedef", s:nord9_gui, "", s:nord9_term, "", "", "")
 hi! link Annotation Decorator
-hi! link Macro Define
 hi! link PreCondit PreProc
 hi! link Variable Identifier
 
@@ -677,7 +674,6 @@ hi! link StartifySpecial Comment
 "+--- Languages ---+
 " Haskell
 " > neovimhaskell/haskell-vim
-call s:hi("haskellPreProc", s:nord10_gui, "", s:nord10_term, "", "", "")
 call s:hi("haskellType", s:nord7_gui, "", s:nord7_term, "", "", "")
 hi! link haskellPragma haskellPreProc