Overlay Refactor

[andrewauclair]

Work in progress of overhauling the internal structure of the FloatListener, DockingUtilsFrame, DockingHandles and DockingOverlay classes.

Currently DockingOverlay is responsible for a long laundry list of overlay features and is heavily reliant on docking regions provided by DockingHandles. These region values are relayed to DockingOverlay through the main DockingUtilsFrame, which gets its updates from FloatListener. This has all become painful to maintain and just read.