Proposal: class that represents the Compiler Command

[Corniel]

While debugging the solution for a bug I stumbled on (more on that later), I noticed that it is quite hard to check what is going in the parsing process of the compiler, and that the logic for C#, VB.NET, and F# is a bit scattered through the code base.

So I decided to spend a day in writing three simple (language specific) tokenizers and parser that creates a typed structure as that represents the compiler command and its arguments, focusing on the type of things we want to query for.

I've all tests working except the original parsing tests. Please let me know what you think.