New pythran interface, TestFromDir() class helper, and a few bugfixes

Multiples things here. The most important changes is a new interface around ToolChain(), the unittests are updated and I expect some failure, not because of regression but because some tests where not executed or the output not compared. This is the case now thanks to a refactoring.

Also a bug fix in pythonic++ (try to run rosetta and you'll have an infinite recursion with gcc 4.8).

"python setup.py test" starts with a "dummy" compilation, just to test the flow/the environment.