Simplify CamWnd mouse handling, remove some specialised freemove handlers.
Remove the FreezePointer::_onMouseMotion member, this was never actually called. Remove corresponding methods in CamWnd.
More refactoring in CamWnd.
Remove ToggleFreeLook option, this is no longer supported.
Don't connect and reconnect the FreezePointer callbacks on each switch.
Detach TexTool from the MouseEvents class.
Remove legacy MouseEventManager.
Remove legacy code from Modifiers class.

Has been mostly taken over by wxutil::Modifier now.
More Modifier code cleanup.
Remove unused state tracking from Modifiers class.
More Modifier code cleanup.
Remove now obsolete Modifiers class.