lexers: prioritize markdown list rule

Reorder the list rule such that it matches before the rule for code
blocks. There are still some problems with multiline list items which
are indented and wrongly matched as code blocks.

lua/lexers/markdown.lua

@@ -68,10 +68,10 @@ local list = token('list',
 
 M._rules = {
   {'header', header},
+  {'list', list},
   {'blockquote', blockquote},
   {'blockcode', blockcode},
   {'hr', hr},
-  {'list', list},
   {'whitespace', ws},
   {'link_label', link_label},
   {'escape', escape},