Merge pull request #31 from lunaskyrise/pixie-dust-tree

Merge PixieDustTree implementation to Master tree
Merge pull request #37 from lunaskyrise/pixie-dust-tree

Merge PixieDustTree and base CeiVMGenerator implementation to Master tree
Revert Semantic-related changes in the Syntax Analyzer tester.
Set policy to specify static void main()'s class.
Fixes #38.