mesh optimization polish (redirect netgen messages to the GUI, etc.)

really simplex cube example

added "Optimize 3D" button in the GUI

We can now use Netgen's optimization pass on our own Delaunay meshes. It seems
to work pretty well on small examples, but it definitely requires more
testing :-)

a version of piece.geo with correct surface orientations so that
it works with netgen

- added small routine to orient all the surfaces in a Surface Loop
  consistently

- fixed orientation of lines/surfaces in holes, *IF* we suppose that
  holes are defined consistently with exterior boundaries (warning:
  there is currently *NO* check for this in the code)

more fixes for netgen

Added hooks to optimize our meshes using netgen (in particular: the "special"
volume 99999 is now cleaned up after use and all the elements/vertices are
transfered back into the original volumes)

As a bonus, this finally allowed me to remove the ugly hacks in the volume
mesh drawing routines...

optimize netgen mesh import (much much faster now for large meshes)

- revert the OPTIM change on 3D_Mesh.o
- fix bustage for --disable-netgen

keep netgen in make source

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!

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.

mention explicitly if a plugin only works for simplices

Generalized Plugin(Triangulate) to handle vector and tensor views

Removed the orientation hacks completely. Should be pretty clean now.

set default RecombineAngle = 75

- %.1g -> %g to display bounding boxes
- update credits

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!)

isolate the hack in a subroutine

another quick hack for non-convex surfaces

pretty print shortcut help

Yesterday's fix wasn't quite right. This should be better.

Horrible hack to fix the surface orientation problems. This is only a
temporary solution: I don't have time to investigate the issue further
right now...

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

create the default project file in the home directory if no "current"
directory is defined (e.g. when double-clicking on the icon on Windows/MacOS)

reset the input lists (do not delete them)

Do a default List_Create in List_CreateFromFile instead of returning NULL.
(This fixes the problems in Plugins that assume that the element lists
are all ready to be added into.)

forgot to destroy the evaluators