Added REPLAY and MAIN MENU button for game screen
Added normal and challenge mode high scores
Merge branch 'master' of https://github.com/ayrten-cofounder/Ayrten-Scrots

Conflicts:
	core/src/com/ayrten/scrots/screens/HighScoresScreen.java
	core/src/com/ayrten/scrots/screens/MainMenuScreen.java
	desktop/highscore_normal_mode.txt