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)

Add VI and SI to adaptiveViews, I hope there was no good reason for the to not be there. It seems to work...

allow multiple optimization passes

move random seed init in GenerateMesh

fix dangerous clean

make sure we define  YY_NO_UNISTD_H on wind32

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)