Enabled editing of Looks and Sounds with new CatrobatListView
Fixed Bug 568 - switching sprites throws null-reference exception
calculate rendertarget + rendertarget size
Adapted FormulaConverterTests; replaced some old test-data-input-xmls (catrobat-lang 0.8) with newer ones (0.91)
Fixed Issues with CatrobatListView and SoundItems (events,...)
Merge TFS Changeset 1718