Made backticks and hash escapable with backslash

I was trying to make a code block with a backtick in it, and it didn't work. So, I made backticks escapable within a code block (line 17) and outside a code block (line 11), although they display as operators when outside.  

While I was at it, I made hash escapable with backslash as well, as per the [markdown syntax guide on daring fireball](http://daringfireball.net/projects/markdown/syntax#backslash).