Initial implementation of multimon support for the Switch interface.
Still needs a preference to govern it.
More explicit expression of if a frame is flipped or cartesian, as a gift to Future Me
Self-review feedback
Make the SWCoreWindowController support setting window groups by dispatch manager.
Cleanup empty line.
Merge branch 'develop' into numist/61

Conflicts:
	Switch.xcodeproj/project.pbxproj
Bugfixes, primarily around window placement.
Basic preferences wiring and interface for multimon.
Safer window group updating when a window controller for a screen does not exist.
Encapsulate property object creation better in setInterfaceVisible:YES
Less confusing naming of NSScreen category methods
Guard to avoid hitting debug checks when the list is loaded and processed before the window controllers have been created.
Merge branch 'develop' into numist/61

Conflicts:
	Switch.xcodeproj/project.pbxproj
Merge pull request #87 from numist/numist/61

Multimon interface support