Undo/Redo on external shapes

Naro had for some time the possibility to load external shapes in Step format. But the problem that Naro was not able to store it as it is because NaroCAD stores high level shapes. For counter this problem was created a shape that stores the shape as is. The single bad problem that this shape was not stored persistently in tree. That means that on operations like Undo/Redo will make Naro simply to crash if is involved an external shape that was not persistently stored. Right now is stored like a binary blob in Base64 format so it can get pretty big but at least solves the problem. One small optimization is that the binary blob is compressed to save space. So the 90k file representing the OpenCascande's sample "screw.step" is compressed to 50k internally (and is that large because Naro uses Unicode strings to save the diff data).

Enjoy importing from now your Step files in Naro!