Sketch: [5/5] Fix up files after splitting SketchObject.cpp
Sketch: [4/5] Move code from SketchObject.cpp to SketchObjectExternal.cpp.
Sketch: [3/5] Move code from SketchObject.cpp to SketchObjectGeometry.cpp.
Sketch: [2/5] Move code from SketchObject.cpp to SketchObjectConstraints.cpp.
Sketch: [1/5] Move code from SketchObject.cpp to SketchObjectOperations.cpp.
Sketch: Refactor SketchObject::getPoint
Sketch: Fix crash when moving sketch with hidden constraints