Syntax highlighting for {=language} ... code blocks (#369)

Author: user202729

syntax/pandoc.vim

@@ -175,7 +175,7 @@ function! EnableEmbedsforCodeblocksWithLang(entry)
         " We might have just turned off spellchecking by including the file,
         " so we turn it back on here.
         exe 'syntax spell toplevel'
-        exe 'syn region pandocDelimitedCodeBlock_' . s:langname . ' start=/\(\_^\( \+\|\t\)\=\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*\.\)\=' . s:langname . '\>.*\n\)\@<=\_^/' .
+        exe 'syn region pandocDelimitedCodeBlock_' . s:langname . ' start=/\(\_^\( \+\|\t\)\=\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*[.=]\)\=' . s:langname . '\>.*\n\)\@<=\_^/' .
                     \' end=/\_$\n\(\( \+\|\t\)\=\(`\{3,}`*\|\~\{3,}\~*\)\_$\n\_$\)\@=/ contained containedin=pandocDelimitedCodeBlock' .
                     \' contains=@' . toupper(s:langname)
         exe 'syn region pandocDelimitedCodeBlockinBlockQuote_' . s:langname . ' start=/>\s\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*\.\)\=' . s:langname . '\>/' .