New box types and game balance

Source code refactor, that allowed for adding new features more easily.
Added 6 new box types with new bonuses. (Now there are 8 instead of 2).
You can now get more speed, a second pad, change velocity of bouncing boxes and get even more boxes.
Nerfed the pad expand bonus to offset the new box types, but it's still OP.
Opened the source code.
More info in the updated project page.