Add Support for Visual Studio 2013

Added Support for Multithreading, has been tested using MbUnit and works, it needs unit tests.

I have made the code compatible with Net 3.5, but if there is a move to .Net 3.5 the ThreadStorage Class that I wrote can be change out for ThreadLocal. In order to keep capability with AlternativeRuntimes (SilverLight and WindowsPhone7) I have used Preprocessor Directives.