new parser engine

- designed and implemented new parser engine for the Catrobat Language => supporting versions greater or equal than 0.93
- all tests for parser classes
- implemented all bricks that are used by our default program (MyFirstProgram)
- converted MyFirstProgram's xml to version 0.93 and replaced the old xml file
- fixed many smaller bugs in DataModel

Note: the parser is still under development but is already able to correctly interpret our MyFirstProgram default program (production ready for this use case). Fallback activated, so that programs downloaded from the PocketCode website are analyzed and parsed by the older parser version. There will be another pull request in the next few weeks after all brick CBXmlParserHandler category-classes have been fully implemented.