Dragging handles

Made a few small steps toward implementing some gizmos. For the moment refactored the shape editing code so that it allows adding custom dragging handlers.
Made the shape editing work for several shapes. At line and rectangle improved the editing so that when dragging by the first shape handle is it changing the shape, previously it was moving the shape.

Drawn extra handles at shapes as triangle handler shapes. With these the problem is that the correct drawing is more complex because shapes are not symmetric so that for correct drawing they need to know the shape plane, the arrows should point "outside" the shape. Refactored all class infrastructure to use instead of 3D points information related to the location and normal to plane where they should operate on. Next step is to make shapes draw correctly relative to the edited shape.