Change latex provider to luatex, closes #476

autoload/vimtex/syntax/p/markdown.vim

@@ -0,0 +1,43 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'latex') == -1
+
+" vimtex - LaTeX plugin for Vim
+"
+" Maintainer: Karl Yngve Lervåg
+" Email:      karl.yngve@gmail.com
+"
+
+function! vimtex#syntax#p#markdown#load() abort " {{{1
+  if has_key(b:vimtex_syntax, 'markdown') | return | endif
+  let b:vimtex_syntax.markdown = 1
+
+  call vimtex#syntax#misc#add_to_section_clusters('texZoneMarkdown')
+  call vimtex#syntax#misc#include('markdown')
+
+  " Don't quite know why this is necessary, but it is
+  syntax match texBeginEnd
+        \ '\(\\begin\>\|\\end\>\)\ze{markdown}'
+        \ nextgroup=texBeginEndName
+
+  syntax region texZoneMarkdown
+        \ start='\\begin{markdown}'rs=s
+        \ end='\\end{markdown}'re=e
+        \ keepend
+        \ transparent
+        \ contains=@texFoldGroup,@texDocGroup,@vimtex_nested_markdown
+
+  " Input files
+  syntax match texInputFile /\\markdownInput\>/
+        \ contains=texStatement
+        \ nextgroup=texInputFileArg
+  syntax region texInputFileArg
+        \ matchgroup=texInputCurlies
+        \ start="{" end="}"
+        \ contained
+        \ contains=texComment
+
+  highlight default link texInputFileArg texInputFile
+endfunction
+
+" }}}1
+
+endif