GFM Enhancements (Backticks)
GFM Enhancements (Backticks)

- Adding support for GFM backticks ``` (for fenced code blocks); in additional to ~~~ already supported in Markdown Extra.
- Adding support for GFM language marker; e.g. ```php
Conflicts:
	markdown.php

jockchou/php-markdown,queirozfcom/php-markdown-with-syntax-highlight,n054/php-markdown,MWDelaney/bootstrap-3-shortcodes,robbieaverill/php-markdown,MWDelaney/bootstrap-3-shortcodes,filipstefansson/bootstrap-3-shortcodes,Kapeli/php-markdown,filipstefansson/bootstrap-3-shortcodes,mariokonrad/php-markdown,ashur/php-markdown,MWDelaney/bootstrap-3-shortcodes