fixed issue #257

fixed #224 (NullPointerException when copying a Sprite containing a formular),
which is last point of #231 CopySprites Tasklist

Jenkins Testrun:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-test/767/

5 iterations of org.catrobat.catroid.uitest.ui.MyProjectsActivityTest:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/516/