save/autosave: unscale meshes and clip planes before saving

[vxlcoder]

[SkaveRat]

Not sure how up to date this old issue is, but I just ran into the problem:

I had a scaled up target mesh. The created RF mesh was therefore also scaled up. Retopo went fine, but an autosave recovery caused the mesh to weirdly scale outwards.

Normalizing the scale of the target and RF mesh to 1 again, also fixed the scaling issue inside RF mode.

The scaled up taget mesh was not intended on my end, so maybe this could be fixed by adding some kind of warning when launching RF when scaled meshes are visible/used