Refactoring in indentation suite

- Activate the indentation test. For this to happen larger
  refactorings were necessary. All the UI dependencies
  needed to be split out of the indentation logic in order
  to avoid triggering of the UI classes. For this a lot of
  code of the internals of JDT is directly copied to SDT.
- Rename TestScalaIndenter to ScalaAutoIndentStrategyTest
- Replace existing test evaluation with the newer one from
  AutoEditStrategyTests