Initial Mark-Selected-Menu
First mark watched implementation
Working marking via context menu on series.
Mark all unwachted slot implemented
Added additional context menu test for marking mixed selected episodes
Refactored main window test to utilize new base class methods.
Set check state traversal
Working IOC cache update while tree traversal
Code cleanup and simplification of tree-traversal on batch-marking.
Merge branch 'feature/MarkAllWatched' into develop

Conflicts:
	seriesmarker/seriesmarker.py
Updated changelog
Updated copyright notice