make clear in docs that node/elemement tags should be > 0 (and not == 0)

corrected some bugs in 2d mesher & occ interface

- save physicals labels when saving unrolled geometries
- fixed crash in unrolled geo save (discrete points)
- Delete Physicals now also deletes the physicals in GModel
- removed unused rules and terminals in parser
- put at least one mid-point when meshing non-straight lines
  in OCC: this fixes most of the trivial 2d meshing problems

set min num pts=2 for OCC circles (fixes bug in Mblade.iges)

- reimplemented subdivision of extruded meshes
- fix indent + unused var + gcc warnings all over the place

cleanup

bidir db: phase 3 -- move all the old geo stuff into Geo/

Enhancement of the OCC interface

Plane surfaces are now recognized and the
usual gmsh "cross" is drawn correctly

occ work

more occ work

:i