Basic parsing using PEG

A full restart of the project, now including both C# & JS implementations of Fools in the initial pass. This includes basic parsing in C#, using a PEG instead of a custom parser.

* Parses empty test declarations, though it cannot run them.
* Cannot execute anything, actually.
* Only parses declarations. There are no statements in the language yet.
* Am not yet sure about the syntax. This parses some Fools-like language, but I am still tinkering with it.