new Tetrahedralize plugin

add missing includes in API for GFaceCompound and SOrientedBoundingBox

missing initAdaptiveData when creating a new view in PView::combine

NMAX should be 8 -> to test by Koen

better pre-fill of solver fields in GUI

stuff, like plugin drawing

Encapsulate toolkit-dependent global drawing functions in new
drawContextGlobal class, and add a static drawContextGlobal to
drawContext, with a default version that does nothing.

This allows to have a completely virtualized drawing system: we can
now ship a library with a fully working graphic system, indepedent of
the widget toolkit. A client code just needs to subclass
drawContextGlobal to get working graphics (see
e.g. api_demos/mainAntTweakBar.cpp)

- pretty print code

set better default char length (avg of existing line ele sizes) in
addOCCMeshConstraints

never ever change the immutable vertex numbers: otherwise we cannot use
our algorithms from outside with prescribed boundary meshes

-> use MVertex::_index instead

(renamed setNum to forceNum to make sure we don't use setNum by mistake)

enhence statreport

make Show/Hide work with GModel entities

fix crash in remeshUnrecoveredEdges