Improvements

Improvement: Application now restores into same state as when was
closed, same documents are open, same selections and cursor positions,
same dirty states

Known issues:
1. Parsing not executed automatically when documents are restored.
2. Document viewport is not restored.

Improvement: removed document recovery - replaced by new functionality
Improvement: Result grid header removed when not result set available
Refactoring: Recovery and History directories replaced by new WorkArea
directory