Master branch should be compatible with master of flixel-addons / flixel
Merge branch 'dev'

Conflicts:
	flixel/addons/ui/FlxUIDropdownMenu.hx
Delete FlxUIDropdownMenu.hx
Merge branch 'dev'
Merge branch 'dev'
Cleaned up DropDownMenu so control_callback is no longer necessary, overlap logic is handled statically now.
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel-ui into dev
Merge branch 'master' of https://github.com/HaxeFlixel/flixel-ui into dev