use brute-force calculation of bboxes if Geometry.OCCBoundsUseStl is set:...

use brute-force calculation of bboxes if Geometry.OCCBoundsUseStl is set: OCC's algorithm enlarges the box by a factor that is hard to predict (combining STL deflection and shape tolerance). While this is safe, it's annoying for our use of bboxes. So let's simply compute the bounds of using the STL nodes and be done with it.