fix: left/right top resize on RectangleTools not working
P11.17: first version
fix: isScreenLocked
test implemented
cleanup
Merge branch 'master' into P11.17_Crash_on_stamp_zoomed_out

Conflicts:
	PaintroidTest/src/org/catrobat/paintroid/test/integration/BaseIntegrationTestClass.java
calculate tool position
tool now centered
Merge pull request #124 from Catrobat/P11.17_Crash_on_stamp_zoomed_out

P11.17 crash on stamp zoomed out
implementation: @landliebe [ML]
acceptance: @galstc05 [SG]