In-game, managers and collisions

So finnally you can login to game and do something (for now you can only
move around with your sprite, but it is looking nice.). And almost
forgot... I added also one boundary box on map. Wooha, you simply cant
evade it. Do you?

Changes in short:
- Made tile engine
- Added gamescreen and menuscreen
- Created map and player managers (base for online integration)
- Fixed small bug in ContentManager and also in GuiManager