Fixes for parenthetical citations (#189)

- Fix parenthetical citations so that it doesn't capture too much.

Without this, a parenthetical citation inside a footnote captures the
whole footnote.
Since we're giving an exhaustive list of all possible characters for
citation keys, we should be greedy in matching them.

- Change highlighting of citations.

Author: bwhelm

syntax/pandoc.vim

@@ -269,11 +269,11 @@ syn match pandocAutomaticLink /<\(https\{0,1}.\{-}\|[A-Za-z0-9!#$%&'*+\-/=?^_`{|
 "}}}
 " Citations: {{{2
 " parenthetical citations
-syn match pandocPCite /\[.\{-}-\{0,1}@.\{-}\]/ contains=pandocEmphasis,pandocStrong,pandocLatex,pandocCiteKey,@Spell display
+syn match pandocPCite /\^\@<!\[[^\[\]]\{-}-\{0,1}@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~\/]*.\{-}\]/ contains=pandocEmphasis,pandocStrong,pandocLatex,pandocCiteKey,@Spell display
 " in-text citations with location
-syn match pandocICite /@[[:graph:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß]*\s\[.\{-}\]/ contains=pandocCiteKey,@Spell display
+syn match pandocICite /@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~\/]*\s\[.\{-1,}\]/ contains=pandocCiteKey,@Spell display
 " cite keys
-syn match pandocCiteKey /\(-\=@[[:graph:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß]*\)\(\]\|\>\)\@=/ containedin=pandocPCite,pandocICite contains=@NoSpell display
+syn match pandocCiteKey /\(-\=@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~\/]*\)/ containedin=pandocPCite,pandocICite contains=@NoSpell display
 syn match pandocCiteAnchor /[-@]/ contained containedin=pandocCiteKey display
 syn match pandocCiteLocator /[\[\]]/ contained containedin=pandocPCite,pandocICite
 " }}}
@@ -569,9 +569,9 @@ hi link pandocFootnoteDefTail Type
 hi link pandocFootnoteBlock Comment
 hi link pandocFootnoteBlockSeparator Operator
 
-hi link pandocPCite Normal
-hi link pandocICite Normal
-hi link pandocCiteKey Identifier
+hi link pandocPCite Operator
+hi link pandocICite Operator
+hi link pandocCiteKey Label
 hi link pandocCiteAnchor Operator
 hi link pandocCiteLocator Operator