Local classes, time module

Local classes were added to the core of Transcrypt.
A time module that closely mimics CPythons one has been contributed.
An itertools module was added as well.
Many small improvements and fixes have been made.

Everything was tested on Windows and Linux.
Should you find bugs, let us know.

It's safe to say Transcrypt isn't a one man effort anymore.
Many thanks to all involved!

Jacques de Hooge