Implement more Unicode compatible alpha character matching

Author: alerque

syntax/pandoc.vim

@@ -304,11 +304,11 @@ syn match pandocAutomaticLink /<\(https\{0,1}.\{-}\|[A-Za-z0-9!#$%&'*+\-/=?^_`{|
 
 " Citations: {{{2
 " parenthetical citations
-syn match pandocPCite /\^\@<!\[[^\[\]]\{-}-\{0,1}@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~/]*.\{-}\]/ contains=pandocEmphasis,pandocStrong,pandocLatex,pandocCiteKey,@Spell,pandocAmpersandEscape display
+syn match pandocPCite /\^\@<!\[[^\[\]]\{-}-\{0,1}@[[:alnum:]_][[:digit:][:lower:][:upper:]_:.#$%&\-+?<>~/]*.\{-}\]/ contains=pandocEmphasis,pandocStrong,pandocLatex,pandocCiteKey,@Spell,pandocAmpersandEscape display
 " in-text citations with location
-syn match pandocICite /@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~/]*\s\[.\{-1,}\]/ contains=pandocCiteKey,@Spell display
+syn match pandocICite /@[[:alnum:]_][[:digit:][:lower:][:upper:]_:.#$%&\-+?<>~/]*\s\[.\{-1,}\]/ contains=pandocCiteKey,@Spell display
 " cite keys
-syn match pandocCiteKey /\(-\=@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~/]*\)/ containedin=pandocPCite,pandocICite contains=@NoSpell display
+syn match pandocCiteKey /\(-\=@[[:alnum:]_][[:digit:][:lower:][:upper:]_:.#$%&\-+?<>~/]*\)/ containedin=pandocPCite,pandocICite contains=@NoSpell display
 syn match pandocCiteAnchor /[-@]/ contained containedin=pandocCiteKey display
 syn match pandocCiteLocator /[\[\]]/ contained containedin=pandocPCite,pandocICite
 " }}}2
@@ -373,7 +373,7 @@ call s:WithConceal("atx", 'syn match pandocAtxStart /#/ contained containedin=pa
 syn match pandocSetexHeader /^.\+\n[=]\+$/ contains=pandocEmphasis,pandocStrong,pandocNoFormatted,pandocLaTeXInlineMath,@Spell,pandocAmpersandEscape
 syn match pandocSetexHeader /^.\+\n[-]\+$/ contains=pandocEmphasis,pandocStrong,pandocNoFormatted,pandocLaTeXInlineMath,@Spell,pandocAmpersandEscape
 syn match pandocHeaderAttr /{.*}/ contained containedin=pandocAtxHeader,pandocSetexHeader
-syn match pandocHeaderID /#[-_:.[:alpha:]]*/ contained containedin=pandocHeaderAttr
+syn match pandocHeaderID /#[-_:.[:lower:][:upper:]]*/ contained containedin=pandocHeaderAttr
 " }}}2
 
 " Line Blocks: {{{2