bidi db: phase 2 -- continued

bidir db: phase 2 -- removed all (well, most of) the old data structures and
algorithms

bidir db: phase 1

temp fix for stephen: call old mesh algo when we don't have MEdgeLoops (i.e. for gmshFaces)

fix crash when trying to draw a geom while the db is being built

Enhancement of the OCC interface

occ mingw

small fixes to cgns + occ win

support for CGNS IO

added FORMAT_CGNS

comment

a start on CGNS IO

removed some unused functors

new != operator
removed some unused functors

added GModelIO_CGNS.cpp

Added CGNS IO

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

occ dvlpt

occ work

fix surfperiodic