AnimationEditor : add key tie mode control in animation editor
AnimationEditor : add key tie mode control in animation editor

ref #4306

hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,andrewkaufman/gaffer