used button in help for back button, refactored help overlay
corrected small bug, that caused wrong position of help overlay in setting screen
used BasicScreenWithBackButton for level group screen
Merge branch 'master' of https://github.com/FAU-Inf2/fly-gdx
made level chooser screen child of BasicScreenWithBackButton, offerend content table for content of BasicScreenWithBackButton
made dialogs more generic, displayed the player name in dialog to delete player, updated space over back button
added renamed file, removed fly id from player screen to get space for back button