- Added main menu
- Added options menu
- Cleaned up code comments
- Created a base HUD class that supports displaying the most recent engine error message and a loading screen
- Added basic network hosting support
- Created empty player state class (for future development)
- Added simple multiplayer map with no bots (test_multiplayer.umap)

* Noted an issue where sometimes the ball falls through the floor after player release (seems to only be from the editor)