Multiple cleanups, made svx::frame::Style a std::shared_ptr class,
preparing basing all border stuff on transformations, so it will
need a CellCoordinateSystem. Added stuff to get this Coordinate
System from the svx::frame::Cell using the Frame and knowledge
about ownerships

Change-Id: Ic2cb59cc92e648ac2fef72f22f8913479769d3e2