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)

You need to submit those changes to the one in monodevelop, we don't need two versions. 

> On 23 Aug 2014, at 13:06, Kevin Ashton <notifications@github.com> wrote:
> 
> In monodevelop/MonoDevelop.FSharpBinding/FSharpSyntaxMode.xml:
> 
> > @@ -0,0 +1,310 @@
> > +<!-- FSharpSyntaxMode.xml
> Nope. I was wrong. The default one has some errors. I am modifying this file and including in next commit.
> 
> —
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