Refactorings in quick fix + refactoring packages

This contains:

- Deletion of AddImportAction because it is unused
- Clean up imports of all components in the packages
- Small stylistic changes
- Additional Scaladoc
Resolves a bug that leads to no quick assistants

This was an interesting bug to fix. What happened here was that we
had a parallel collection that swallowed an exception. Because the
exception was never shown to the outside world it was not possible
to find out what went wrong. I managed to get the exception by
removing the parallel collection, which was done not because I knew
what to do but because the parallel collection looked unnecessary.

The exception itself was due to an unescaped string that is interpreted
as a regex and could easily be fixed. It occurred whenever one selected
a method with a symbolic identifier like '+'.

More interestingly, even after the fix of the bug the code with the
parallel collection still didn't work - it just returned an empty list.
I have no idea what went wrong but I believe its a problem somewhere in
the internals of the parallel collection - thus no usege of it anymore.

Fixes #1001801, #1001798
Merge pull request #477 from sschaef/t-quickfix-fix

T quickfix fix
Refactorings in ScalaSourceViewerConfiguration

The order of parameters in the constructors of the scanner classes
has changed.

All other changes are formatting related.
Merge pull request #432 from sschaef/t-refactor-source-viewer

Refactorings in ScalaSourceViewerConfiguration
Delete old plugin signatures
Merge pull request #478 from sschaef/t-delete-old-signatures

Delete old plugin signatures
Removes reference to non-existing command

Fixes #1001807
Merge pull request #480 from skyluc/issue/no-command-for-restart-pc-1001807

Removes reference to non-existing command