Preference to Specify Default Windows in a Perspective

It should be possible to specify what windows are open by default for each perspective.

This should apply when switching to the perspective or when starting SmartGit.

The simplest would be to be able to specify the set that was last in use.

SmartGit 21.1.1 now always shows the "changes" window, which I now always have to get rid of, as it usually gets in the way.