More "airplane" work...

- rewrote the way we handle lights: glEnable(GL_LIGHTING) is now used
  at the lowest level, where it belongs. This fixes many lighting
  glitches, and should make the whole stuff much more predictable;

- simplified the display modes for geometry and mesh: the choice
  between wireframe/solid is now independent of the choice of
  lighting/no lighting (and there is a new "Enable lighting" option
  for the geometry, too--even if it does only affect things like
  normals/tangents at the moment);

- brand new code to draw really nice (shaded) 3D arrows + 3 options
  that fully parameterize them (they can degenerate into pyramids,
  cones, w/ or w/o stems, etc.);

- new options so that we can also use the new arrows outside the
  post-processing module (e.g. for tangents/normals).

- "alt+d" now simply switches between solid and wireframe mode;

- new shortcut "alt+w" to switch the lighting mode for all the modules
  (geo/mesh + all post views) at once.

Update copyright notice

better -convert

Added "append" argument to WriteView (so that "gmsh -convert file file"
can handle all the views in the input file and not only the first one).

Following a discussion with Laurent, we can now combine multiple views
(under certain conditions) into multi time step ones. This permits e.g.
to output separate .pos files for each time step, and still have a real
time evolution in gmsh. Pretty neat :-)

New post-processing range mode to adapt the scale for each time step (i.e.,
min/max is time step dependent)

Cleaned up the whole Include/Merge/Open mess (removed the ugly
yyin/yyname tables in the parser, made the Merge routine reentrant
+ uniformized all the INFO/STATUS messages).

This should fix a nasty side effect from this morning's
commit (wrong yynames when doing multiple merges in the same
file).

Prepare for commercial release

Save the chosen FLTK theme in the per-session resources

Fix a couple of bugs for 2nd order elements. Seems to work OK for 2D
meshes now. 3D is still kinda flaky, and extrusion is not implemented.

- add PNG check in Get_BuildOptions()
- move "make doc" to top-level Makefile
- better "make purge"

Corrections apres relecture / part 1

Added shortcuts.texi

Fix whitespace in copyright headers

pretty print build options

pretty print build options

Make headers self-contained

add progname in -info

GPL -> General Public License

License stuff

Indented all source files using utils/gmshindent

Add some indent directives

Clean up VERSION_FLAGS and OS_FLAGS (use HAVE_FLTK instead of _FLTK,
remove _BLACKBOX, etc.)

Updated copyright

Introduce OpenGL display lists for drawing meshes. Does not seem to
work much faster on my machine, though.

Fix make source

- Cosmetic changes in 'File->Save as' menu
- 'flattened geometry' -> 'unrolled geometry'

Interface polish (buttons should not be resized when the size of the window is changed);
gl2ps update (not finished);