Launches.
Made sure slideshow images are disposed when clip is changed.
Tidied up creating transitions.
Merge branch 'OverlayPlugin' of github.com:JohnMcCaffery/Chimera into OverlayPlugin
Simplified factory based instantiation.
Moved IImageTransitionFactory to IFactory.cs
Adding foundations for overlay plugin GUI.
Basic GUI implemented for overlay plugin.
Renamed WindowTransition to TransitionStyle.