Remove native app

Removal of NativeApp and all associated code. As you can see from the commits, I had to refactor some parts of the Parser.

[Successful testrun](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-test/138/)

**Note**
Because we recently began normalizing line endings, the diffs on github are not so useful. Use *git diff -w* to ignore whitespace changes to get a better diff.

If you are not comfortable with the command line, [here's the diff online](https://gist.github.com/eaba9509320bfff483e4)