- all keyboard-related stuff moved into PhysicalKeyboardHandler class
- all snapshot-related stuff moved directly into PNGLibrary class
- EventHandler class is now ~1300 LOC, which while still large, is much better than 2500 LOC
For now, joystick-related stuff is moved into its own classes.
No improvements are made yet; just refactoring and moving code around.
This reduces EventHandler from ~2500 lines to ~2000 lines.