Reworked PointerMapping Hover/Active model. Added ConnectionWidget.

Added m_CurrentPointerMappingTEST which is current mapping (updated at
all times, regardless of pointer capture).
Removed m_PreviousPointerMappingTEST because now PointerMapping is
updated _after_ pointer is deactivated, so previous widgets get last
deactivated events.
Widget::GetHover() returns true if directly hovering.
Widget::GetActive() returns true if directly active and button 0 is
down.