make it possible to add second order vertices for a mesh read from
a file (without cad)

use it now with -partition N for N partitions
only works with tets and triangles
output should be added (useless for now)

compile tetgen by default so we get feedback on machine-specific problems

All modifications are commentarized because
this feature is not functionnal : the transfer from
Gmsh to Tetgen is OK, but the transfer from Tetgen to
Gmsh is not : all the mesh (points, lines,
surfaces, volumes) must be recreated in Gmsh...

don't store lines in vol->Simp_Surf : it screws up the saving of Physical
Lines! Use vol->Lin_Surf

remove the VerticesTemp hack, as it was not the main bottleneck

Removed the last bits of the "Discrete Surface/Line" stuff.

Gmsh can now simply read a .msh file, and use it as the boundary mesh
of a 3D mesh. For an example on how to do this, cf.
demos/sphere-discrete.geo.

This complements nicely the STL remeshing stuff: Gmsh can now
for example very easily be used to extrude surface meshes that
come from other tools.

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

removed unused stuff + handle SURF_DISCRETE in MeshDiscreteSurface

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

- 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

removed remaining Discrete Line/Surface stuff

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

- 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

- removed all the crappy STL code and rewrote it using JF's POLY_rep
  class

- generalized POLY_rep so that we can use the polygonal discretization
  as a surface mesh, and mesh in 3D afterwards. I.e., we can now take
  an input triangulation (a single surface in STL format, multiple
  surfaces in STL format, one or more surfaces defined using the new
  "Discrete Surface" commands), and generate a 3D mesh that uses it. We
  could in theory even mix triangulated and "normal" surfaces in the
  same geometry, but nothing is done at the moment to ensure that the
  mesh at the interfaces would match (if it does, it actually works
  very nicely)

- new STL mesh output format to export a surface mesh as a STL file

- added an option to the GEO output routine to save the surface mesh
  as discrete surfaces associated with the geometrical surfaces

- added STL and Text output formats for post-processing views (the
  text output allows for example to exploit plugin-generated data in
  gnuplot)

- generalized Plugin(Evaluate):

  * can loop automatically over all the timestep and/or components

  * can do operations using data from an external view

     - if the 2 views are based on the same grid, the plugin does the
       evaluation very efficiently

     - if the 2 views are based on differenet grids, the plugin
       automatically interpolates the external view data onto the
       grid of the current view

- added new Rand() function in MathEval

- default colormap is now # 2 (the Matlab "Jet" colormap)

copyright update

generalized ExportLcField to all element types

- reworked the keyboard shortcuts with Laurent (our very own Macintosh
  Usability Guidelines Expert)

- new smoothing option for jpeg output

- new small GUI dialogs for ps/pdf/jpeg/gif/msh output (makes the
  'format' menu in the file dialog much shorter)

The "Simplex" class is now derived from a new class "SimplexBase",
which contains only pointers to the nodes, and none of the other stuff
necessary for the actual mesh generation.

All the input/output/display routines have been rewritten in terms of
SimplexBase: this provides a gain of almost 50% in memory when you
just load meshes from .msh files to do visualization stuff, instead of
actually generating the mesh.

added vertex arrays in volumes to store the boundary of the cuts
when we draw them "as surfaces" (for Philou, not tested yet)

- moved the smooth normals stuff into a separate file
- added smooth normal support for surface meshes (very nice!)

- Triangle now supports our background meshes

- fixed memory leak in Optimize_Netgen (forgot to free the volume
  vertices) + added missing 2nd order reset

- fixed a couple of typos in the docs

added optimization hooks in the interface (GUI + comamnd line)

refactor the netgen code in a dedicated class

Merged Netgen 4.3.1: a Delaunay/Frontal 2D/3D mesh generator.

Thanks a lot to Nicolas Tardieu for this!

Store the surface orientations (from surface loops) in the volume: we need
this for Netgen.

Replaced my orientation hack with a rigorous algorithm... Seems to
work nicely (and is general).

Apply the surface re-orientation hack to quadrangles (and to extruded
meshes!)

- mesh.algo -> algo2d and algo3d
- replaced most of the remaining radio buttons with Fl_Choices (requires
  less screen real estate)

- generalized vertex arrays to handle quads

- added missing Ellispe ... Plane ... in parser

- generalized vertex array class to use reallocatable arrays

- introduced vertex arrays in post for all triangles: this speeds
  things up tremendously for ALL scalar views: 2d scalar views of
  course, but also for 3d isos (tets, hexas, etc.) and all smooth
  normals. The costly computations (compute the isos, get the normals)
  are only done ONCE each time the view is changed. Then we just pass
  the vertex array to OpenGL everytime we need to redraw (e.g. when we
  rotate the scene)

- removed the display list code alltogether: it's completely blown
  away by the new vertex array code!

for the record: with the new drawing code, you can

- rotate 500,000 triangles in real time on a 3-year old linux PC
(tested with a boing 747 surface mesh from CU: 10 times faster than
old code)

- display and rotate in real time 10 transparent+smooth shaded 3D isos
for a 1 million tet mesh (about 1 frame per second with the new code;
took tens of seconds with the old one)

Awesome :-)

- added experimental support for vertex arrays in the mesh drawing code
(only for triangles at the moment). This speeds up the drawing of large
meshes tremendously!

- removed support for mesh display lists

Added final bit for 2nd order elements: the middle face nodes for
quadrangular faces (i.e., for quadrangles, hexahedra, prisms and
pyramids).

- removed the quads from the simplex trees (finally...)

  **warning**

  this is a pretty big patch that touches a lot of different files. I
  tried my best to update all the things that needed to be updated,
  but I probably forgot some things... Please test! (especially the
  export routines in obscure formats like SMS, Gref, etc., as well as
  the extrusion code)

- added second order edge vertices for hexas, prisms and pyramids
  (drawing not done yet)

- added sanity check for number of values in post-pro parsed file
  format

- merged all mesh printing/reading routines in Print_Mesh.cpp and
  Read_Mesh.cpp

- cleaned up the statistics code

- store the points required by the transfinite algo in a list of vertices
  (instead of surf->ipar, vol->ipar)

- generalized Coherence for these lists of transfinite points