Inclusion of FormulaEditor in Scriptactivity.

* onKeyback events now will be send from scriptactivity to visible FE-fragment.
* Tags added in Look-, Script-, Soundfragment.
* Actionbar will be updated in every FormulaEditor fragment.
* FormulaEditorFragmentTest (UI) updated.
* FormulaEdtiorKeyboardTest (UI) updated.
Update of FormulaEditorEditTextTest (UI)
scrolldown() methods remove from FE-tests (UI)
Minor refactoring in UI-test classes
Remove of euler(math) test.
Merge branch 'FormulaEditor' of https://github.com/Catrobat/Catroid into FormulaEditor