Added Identifier token type
Added some incomplete grammar for Vala in bnf format. Now ValaLexer is generated using Grammar-Kit plugin from grammar itself.

First dummy vala source file parsed. Yay!
Introducing mostly complete Vala grammar. Still need to work on string and number literals
Improved grammar, works for simple cases
Parsing works for more complex example. Generated tree needs to be optimized though...
Added missing parser test expectations
Replaced parser expected trees with proper ones. First test for referencing objects
First working reference resolution! Also flattened the AST trees using the "extends" clause in .bnf file