Prevent embedded language syntaxes from changing 'foldtext' (#352)

Analogue to tpope/vim-markdown#173

Author: Konfekt

syntax/pandoc.vim

@@ -162,6 +162,7 @@ function! EnableEmbedsforCodeblocksWithLang(entry)
     " prevent embedded language syntaxes from changing 'foldmethod' 
     if has('folding')
         let s:foldmethod = &l:foldmethod
+        let s:foldtext = &l:foldtext     
     endif
 
     try
@@ -183,6 +184,9 @@ function! EnableEmbedsforCodeblocksWithLang(entry)
     if exists('s:foldmethod') && s:foldmethod !=# &l:foldmethod
         let &l:foldmethod = s:foldmethod
     endif
+    if exists('s:foldtext') && s:foldtext !=# &l:foldtext
+        let &l:foldtext = s:foldtext
+    endif
 endfunction
 " }}}2