Allowed . in markdown language blocks

Updated markdown highlighter to allow stuff like ```python.run

lib/ace/mode/markdown_highlight_rules.js

@@ -79,7 +79,7 @@ var MarkdownHighlightRules = function() {
        github_embed("css", "csscode-"),
     { // Github style block
         token : "support.function",
-        regex : "^```\\s*[a-zA-Z]*(?:{.*?\\})?\\s*$",
+        regex : "^```\\s*[a-zA-Z\.]*(?:{.*?\\})?\\s*$",
         next  : "githubblock"
     }, { // block quote
         token : "string.blockquote",