Stage performance quick fix

Currently, all non blocking bricks need at least one entire frame for execution. So it seems, that the stage is slow and unable to put up with complex animations. But in fact, computation time is wasted.

The quick fix solves these problems by using a small delta for the actions to update. Instead of refreshing the actions for one time with "delta", the actions are refreshed "n" times with "delta / n".

A short video, which demonstrates the performance differences:
https://dl.dropbox.com/u/42800985/ActionsPerformance.mp4

Complete Jenkins testrun:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-test/639/