Explicitly say that the mesh will be incorrect if the swapping failed

Fixed one more bug for degenerate, non-recombined extrusions, that could
lead to duplicate elements.

Fix seg fault in Read_SMS

Fixed degenrate tets generation (oops!)

- new DecomposeInSimplex plugin
- new "Combine Views" command in the parser
- cleaned up View::tranform and View::smooth (+small bug fix for SLs)
- better check for transparency sorting
- make depend
- new View.AlphaChannel option to change the transparency
  globally for a given view (instead of having to change the colormap
  by hand every time)

With all the above, we can now generate very nice (and correct)
transparent iso-surfaces:

Merge "../tutorial/view3.pos";

minIso = 0;
maxIso = 2;
nbIso = 7;

Plugin(CutMap).iView = 0;

For i In {1:nbIso}
  Plugin(CutMap).A = (maxIso-minIso)/nbIso * i;
  Plugin(CutMap).Run;
EndFor

Delete View[0];
Combine Views;

For i In {1:nbIso}
  Delete View[0];
EndFor

Plugin(DecomposeInSimplex).iView = 0;
Plugin(DecomposeInSimplex).Run;

View[0].AlphaChannel = 0.6;

Fix name

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).

Fix 2 gcc warnings

- Fix element numbering in Extrude Point and Extrude Line
- Look for config files in $GMSH_HOME before $HOME

- Comment JF's last changes in the parser until we fix the syntax

- Update gl2ps

- Small fix in the configure script to better detect fltk-config

- Fix Parser/Makefile (for older versions of bison)

New native PDF support

Make it possible to change Triangle options

Don't optimize 3D_Mesh.

polish

Remove 2nd order for 3D altogether, since it still produces incorrect
meshes if edges of the surface mesh get swapped

forgot this one

Shout if we try to generate second order meshes in non-implemented
cases.

Some morer work on second order elements

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.

Added warning + option for circle/ellipse arcs >= Pi

Speed up variable creation/retrieval by replacing 'List_T *Symbols_L'
by 'Tree_T *Symbols_T'.

forgot to create physical points

Fixed a couple of gcc warnings

Added PNG support

Fix comparison with uninitialized variable (found using valgrind).

Fix whitespace in copyright headers

Add missing copyright headers

Add Contributor(s) where due.

Cleanup NR includes

Cleanup Tree_Replace/Tree_Insert + better error detection in Read_Mesh.

typo

Remove garbage

Add Layer on Extrude Point (phase 2 -- remove duplicates)

Fix race condition

Fix crash due to identical vertex pointers in Mesh.Points and
Mesh.Vertices