Improvements to the PyBoy interface

Improves solution in #36

Many PyBoy-related topics still need to be tuned to provide a good enough API-compatible solution.

The current solution does not capture the "screen" well enough to automatically run simple games like Tetris. This must be changed by handling the underlying compatibility requirements - currently the post_tick() call seems to be causing issues.

These are the main goals of this MR:

• Support for emulation speed control
• Properly capture screen to provide Tetris level compatibility layer
• Tetris values capture, allowing Tetris demo to run (gamewrapper_tetris.py)