Be more Unicode compliant

Closes #264

[:alpha:] only gives you ASCII alphabetic characters. [:upper:][:lower:]
gives you all of them, including stuff like "ẽ", which is used for
writing many South American indigenous languages.

Author: rafaeln

syntax/pandoc.vim

@@ -437,7 +437,7 @@ endif
 syn match pandocListItemBullet /^(\?.\{-}[.)]/ contained containedin=pandocListItem
 syn match pandocListItemBulletId /\(\d\+\|\l\|\#\|@.\{-}\|x\=l\=\(i\{,3}[vx]\=\)\{,3}c\{,3}\)/ contained containedin=pandocListItemBullet
 
-syn match pandocListItemContinuation /^\s\+\([-+*]\s\+\|(\?.\+[).]\)\@<!\([[:alpha:]ñäëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_"[]\|\*\S\)\@=.*$/ nextgroup=pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocDelimitedCodeBlock,pandocListItemContinuation,pandocListItem contains=@Spell,pandocEmphasis,pandocStrong,pandocNoFormatted,pandocStrikeout,pandocSubscript,pandocSuperscript,pandocStrongEmphasis,pandocStrongEmphasis,pandocPCite,pandocICite,pandocCiteKey,pandocReferenceLabel,pandocReferenceURL,pandocLaTeXCommand,pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocAutomaticLink,pandocFootnoteDef,pandocFootnoteBlock,pandocFootnoteID,pandocAmpersandEscape contained skipempty display 
+syn match pandocListItemContinuation /^\s\+\([-+*]\s\+\|(\?.\+[).]\)\@<!\([[:upper:][:lower:]_"[]\|\*\S\)\@=.*$/ nextgroup=pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocDelimitedCodeBlock,pandocListItemContinuation,pandocListItem contains=@Spell,pandocEmphasis,pandocStrong,pandocNoFormatted,pandocStrikeout,pandocSubscript,pandocSuperscript,pandocStrongEmphasis,pandocStrongEmphasis,pandocPCite,pandocICite,pandocCiteKey,pandocReferenceLabel,pandocReferenceURL,pandocLaTeXCommand,pandocLaTeXMathBlock,pandocLaTeXInlineMath,pandocAutomaticLink,pandocFootnoteDef,pandocFootnoteBlock,pandocFootnoteID,pandocAmpersandEscape contained skipempty display
 " }}}
 " Definitions: {{{2
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