fixed bugs + start new background system

Fixed crash when no tiles where used, onscreenbuttons now use Rect
instead of RectF.
Merge remote-tracking branch 'origin/master' into Paul_branch
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changed collision to work with new tile system

Alarms are broken since merge with paul_branch :( .
Added starting point for student
Mege with Paul_Branch
added functions + MyGame starts vissenkom

Functions for custom rendering + object touch detection added.
Merge branch 'master' into Paul_branch