fixed full-quadrangle recombine algo:

- run globally, not for each surface
- assign entities to elements
- split line meshes
- correctly re-tag vertices as 1st order
- plug memory leaks

replaced ExportLCField with ExportMeshStatistics (lc + gamma, eta, rho + elem num)

removed unused stuff + handle SURF_DISCRETE in MeshDiscreteSurface

add num of physical groups in stat window

Fixed performance problem(s) for very large meshes with a huge number of
physical entities:

1) use a temp tree for physical entities in read_mesh

2) we should not set partition=physical for the old mesh format

3) only do getFirstPhysical in draw_mesh if we need to (and warn if
   we do and if there are many many physicals)

polih previous commit

2 big optimizations for meshes that contain a lot of line elements:

- speed up Read_Mesh (by introducing temp tree in curves)
- use vertex arrays for lines in mesh drawing code

make the extrusion stuff work with SimplexBase too

make the code compile on Mac OS X 10.4 (gcc 4.0.0)

- removed the "Dirty" flags in the CAD data structures

- when reading the mesh from an entity that has no CAD, create a "discrete"
  CAD entity

- remove the drawing of discrete entities that don't have a BDS
  representation during the geometry drawing

make it compile on my mac

removed remaining Discrete Line/Surface stuff

initialize bds=0 by default, so that at least the code does not crash when
doing normal things ;-)

- fixed a couple of warnings

- JF: bds.classify crashes in recur_tag on simple examples (demos/sphere-stl.stl)

smaller lc files (%.16g -> %g)

- Generalized the "View" parser so that we can add new elements more easily
  (the code is *much* shorter, but unfortunately about 10-15% slower)

- Upgraded all post-pro file formats to handle curved (second order)
  elements: SL2, VL2, TL2, ST2, VT2, ... The new version number for the
  postpro files is 1.4

- Added code to automatically split the curved elements into linear
  elements when the view is created. WARNING: this is only a temporary
  solution: weshould generalize Adaptive_Post_View to handle these curved
  elements.

damn, fix division  by zero in Progress() if we have less than 10 nodes
in the mesh

treat quads in poly_rep_to_mesh: this way we can also extrude discrete
surfaces meshed with quads

Merged patch from Matt Gundry <mjgundry@faa-engineers.com> to support
the structured Plot3d mesh format.

smaller init alloc in curves

Use the curve's end points id numbers for the end vertices (as we do
in the normal 1D algo). This is what the old extrusion algorithm
expects.

fixes for discrete curves/surfaces

copy/paste bug

modified Read_Mesh and Print_Geo so that we can save line/surface meshes
loaded from a file as discrete geometries

- New "Discrete Line" commands (similar to the Discrete Surface commands, but for
  curves).

  This permits e.g. to use Gmsh's extrusion mesh generators on 2D meshes (with
  boundaries) imported from other programs, and have all the useful elements
  generated (both volume and surface).

- Don't use Ctrl+m for File->Merge, as it is a reserved keyword for
  Window->Minimize on OS X:
  * File->Merge is now Shift+Ctrl+o (since it's in some way a variation of
    File->Open's Ctrl+o)
  * Tools->Options is now Shift+Ctrl+n