Refactoring of loading levels. Removed from GameScreen into its own class.
Merge branch 'master' of https://github.com/machpavel/autickax

Conflicts:
	Auticka/src/cz/mff/cuni/autickax/scene/GameScreen.java
	Auticka/src/cz/mff/cuni/autickax/scene/TitleScreen.java