Official D Grammar

[Brian Schott]

I've moved my work on the grammar to the following location on 
Github:

https://github.com/Hackerpilot/DGrammar

This uses ANTLR, as the other parser generators can't handle D's 
grammar. Several rules from the official grammar were removed, 
and several others were added (Such as an actual rule for a 
function declaration...) I also tried to fix any inacuracies or 
omissions I came across in the online documentation.

Comments, issues, and pull requests welcome.