Refactored the editing handle dragging functionality to use actions. This assures a better code separation. There are still bugs to solve at this code.
Implemented the Gizmo infrastructure and implemented a first version of the translate Gizmo. The translation Gizmo will have 3 arrows allowing the user to drag the shape on the 3 axis and 3 planes that will allow the user to move the shape on the 3 planes: XOY, XOZ, YOZ. It is not working properly yet.