Refactoring in indentation suite

- Activate the indentation test. For this to happen larger
  refactorings were necessary. All the UI dependencies
  had to be split out of the indentation logic in order to
  avoid a 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