vellum 0.17: refactorings and sweetness

Written for Vellum by ronny on 2009-07-30

This is the next release of vellum, there have been some interesting changes

The Parser is rewritten in pure Python.
The setup.py generator builds more nice python files now.
You can tell vellum to change the cwd before starting.
Options now get passed to sub-processes as part of the environment.