Add support for gnuplot nested highlighting (#514)

after/syntax/tex.vim

@@ -189,6 +189,18 @@ syntax region texZone
       \ contains=texBeginEnd,@LUA
 let b:current_syntax = 'tex'
 
+" }}}1
+" {{{1 Nested syntax highlighting for gnuplottex
+unlet b:current_syntax
+syntax include @GNUPLOT syntax/gnuplot.vim
+syntax region texZone
+      \ start='\\begin{gnuplottex}\(\_s*\[\_[\]]\{-}\]\)\?'rs=s
+      \ end='\\end{gnuplottex}'re=e
+      \ keepend
+      \ transparent
+      \ contains=texBeginEnd,texBeginEndModifier,@GNUPLOT
+let b:current_syntax = 'tex'
+
 " }}}1
 " {{{1 Nested syntax highlighting for minted
 

test/features/syntax/test-syntax.tex

@@ -27,6 +27,10 @@ testing
   }
 \end{dot2tex}
 
+\begin{gnuplottex}[terminal=..., terminaloptions=...]
+    plot file using 1:2 with lines
+\end{gnuplottex}
+
 \begin{minted}{python}
 def function(arg):
     pass