- clean up GModel API (xxByTag -> getXx, numXx -> getNumXxes, ...)

make it easier to see when char lengths are bad

ooops!

Smoother Surface{list} = numsteps;

removed unused fct

removed GFace::GraphicsRep and reimplemented it using the more general
STL vertex array

rewrote Pplugin(Triangulate) to use our in-house divide and conquer algo
removed triangle from contrib
reactivated OCC STL meshing

- fixed embedded version
- removed OCC STL meshgen for now (OCC/triangle clashes with our own version
of triangle)

removed vestiges of "discrete point" hack in gmshVertex & co (now that
we have the correct discreteXXX classes)

bbox drawing of geo entities for debug (disabled)

fix dangerous clean

A minimal Gmsh "null" model can now be embedded with no external dependencies

API cleanup: new discreteVertex, discreteEdge, ... entities (replacing
the old hacks in gmshVertex, gmshEdge, ...), the future basis of the
indepedent "null" model (cf. HAVE_NO_GEO define)

API cleanup: FVertex, FEdge, etc. -> fourierVertex, fourierEdge, etc.

API cleanup: removed unused functions