* new occ/getBoundingBox and occ/getEntities to remove the need for some synchronizations when building large models

bounding entities are also discrete (without parametrization!), i.e.
if the whole brep will not be meshed.

This fixes the crash we'd get if we reparametrize e.g. a surface
on the boundary of a discrete volume; the discrete volume mesh
becomes invalid (linked to deleted nodes on its boundary)

- use GEdgeLoop to compute signs in setBoundEdges()
- remove _orderMLines, so that createGeometry() does not modify the mesh anymore
- appply equivalement of _orderMLines only when creating compounds (for which the mesh needs to be reordered)