cleaned comments
small simplification and change in Script class
terminology corrected; function renamed

* cleaned: corrected uses of "Scratch brick" to "Scratch block"
* cleaned: renamed converter functions
* deleted: unused method in Script (scratch)
removed unused values in test
doPlaySoundAndWait brick added

* added: doPlaySoundAndWait brick support
* added: support-functionality for above brick (common, catrobat)
* changed: some renames to improve readability
added in-memory raw Scratch project creation

* added: in-memory creation of raw Scratch project
* changed: Scratch project creation methods refactored
* added: separate web request method of project code
refactored and extended Scratch tests

* added: test for Scratch variables access
* changed: removed use of scratch.Project in Object tests
* added: Scratch Json test structure
* removed: unused class member (scratch.Object.is_stage_object)
removing project variables from Scratch stage object