SideBySide2: Add syntax highlighting for 18 more languages

Include more languages into the CM3 mapping supported by Gerrit:

* coffeescript
* d
* diff
* dtd
* erlang
* gas
* gfm (GitHub Flavored Markdown)
* haskell
* lua
* markdown
* php
* pig
* r
* scheme
* smalltalk
* tcl
* verilog
* yaml

Change-Id: Ie3cc3657183a475fb71a71e0fe35be848deb985f
(cherry picked from commit 5478148f6f25db215424f51d6a5e88f7bf78f164)
5 files changed