Add Toggle Comment support for several more languages

Toggle Line and/or Block Comment support for: Java, CoffeeScript, Perl, Ruby, Python, SASS, Lua, Markdown, YAML, Haxe.  All these languages were included in core already.

I hit a few snags while working on this:
* CoffeeScript supports block comments via `###`, but Toggle Block Comment behaves badly (I think because the open/close delimiters are identical).  So I've only included lineComment for now.  Filed #3057 on this.
* I wasn't clear on whether Ruby officially supports block comments.  I've seen mention of `=begin` and `=end` but couldn't find any real-world code that uses this (and I'm not clear what the "rules" are -- e.g. do those delimiters have to be alone on a line?).  So I only included lineComment for now.
* Clojure supposedly supports line comments, but people seem to use `;` and `;;` equally.  We'd probably want uncomment to fully strip either flavor, which we don't support yet.  But Clojure being functional, _toggling_ line comments also seems very rare -- toggling block comments might be useful, except it seems Clojure doesn't offer block comments.  So I've left Clojure out for now.