Added copyrights.
Comments, preferences dialog correction.
Tags can be set for multiple items at once now.
Removed unused method.
Added rubberBand selection.
Slightly corrected tagsRepack, and selection highlighting.
Code cleanup in TagBrowser.
Added debug dialog.
Added ability to save and restore main window state and position.
Additional options for DerpibooruProvider.
Fixed DebugDialog freezing bug.