i116: Testcode and first implementationtry
implementation fixed
Merge remote-tracking branch 'origin/cleanup_testcase' into I116_undo_after_crop
Merge branch 'master' into I116_undo_after_crop
Change resetInternalState to be more flexible for different tools
no canvas.restore needed, only leads to Exceptions without canvas.save
before
crop reacts to new image/load image
fixed test which used reflection for old signature of resetInternalState
Merge branch 'master' into I116_undo_after_crop
move the controlling part of resetInternalState into Basetool
Merge pull request #142 from Catrobat/I116_undo_after_crop

I116 undo after crop
Implementation: @landliebe [ML]
Acceptance: @galstc05 [SG]