A First step towards better syntax highlighting

This is the first stage of better syntax highlighting. It currently handles greying out blocks that are conditionally compiled out, multiline block comments and multiline strings, as well as highlighting of classes. Comments and criticisms welcome. 

Has not been testing on OS/X, but has been tested on Windows.

See below screenshot for an example: 

![image](https://cloud.githubusercontent.com/assets/1762752/4013831/7a2c0200-2a1a-11e4-86c4-d11886cad04a.png)

Based on our discussions on StackOverflow chat, do we move this back to the F# Binding, or leave it in MonoDevelop. My view is that we can do both. We can include an updated version here, which will supercede the one in the MonoDevelop repo, so we are not tied to the MonoDevelop release cycles, but we can also leave the one that is in there and update it as this one is enhanced.