Adapted structure of IDE tests
Added Test-categories and adapted ViewModel-tests
Replaced last xaml-appearances of old ThemeChooser within the IDE (class structure of ThemeChooser is still present)
Project-description: removed HTML-tags and limited number of whitespace-characters
Added tiles and splash screen for Paint app
Improved and fixed sharing and uploading programs
Changes in Theme colors
Added seperate View for catrobat license info
Changes in error handling of FormulaEditor
Fixed broken tests
Merge TFS Changeset 1561