Fix citation definitions

Closes #191

For citation definitions, `/` does not need to be escaped when included
in `[ ... ]`, so having `\/` will match either `\` or `/`. We don't want
the `\` character.

Author: bwhelm

syntax/pandoc.vim

@@ -275,11 +275,11 @@ 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:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~/]*.\{-}\]/ 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:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~/]*\s\[.\{-1,}\]/ contains=pandocCiteKey,@Spell display
 " cite keys
-syn match pandocCiteKey /\(-\=@[[:alnum:]_][[:alnum:]äëïöüáéíóúàèìòùłßÄËÏÖÜÁÉÍÓÚÀÈÌÒÙŁß_:.#$%&\-+?<>~\/]*\)/ 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
 " }}}