add little menu to choose the quality measure in Options->Mesh->Visibility

fixed small bug when drawing the boundary of a prism for a time step > 1

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

add note to remember how to use compiled vertex arrays

removed unused stuff + handle SURF_DISCRETE in MeshDiscreteSurface

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)

optimize 2d iso plots with vertex arrays

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

update to latest gl2ps

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

- changed "View.ArrowLocation" into "View.GlyphLocation" (this way we can
  also use this option to display the numeric values at the nodes,
  instead of displaying always at the barycenter)

- changed the numeric display of vectors (display the 3 omponents
  instead of the norm)

add line stippling for 2d plots

removed unused Post.Scales option

better subdivision scheme for drawing scalar hexahedra (with edges matching
on opposite faces)

axes color

new option to control a view's axes color

add missing line width spec

fix small bug in center-align for TeX output

- better test for drawing geo+mesh bbox
- ask if we want to uncompress gz files during merge

make center/right-align work for scales and 2d-plots, too

added a 5th axes mode: "Ruler" to help measure distances between any two
points

polish the last commit some more (activate/deactivate widgets, etc.)

a little more work on the axes stuff: enable global axes for the geometry and
the mesh, too. We can finally get rid of the ugly old "moving axes" bit.

(+ reverted changes in unproject: need to be more careful since unproject
can be called outside Draw())

- added an option to force the size/position of the 3D grids/axes

- cleaned-up the whole size/position thing of 2D/3D grids: it's much
  more consistent now (and the GUI is nicer)

- rewrote the algorithm for automatic positionning of 2D graphs (now
  they rescale with the window, which is much nicer--and far more
  practical)

- cleaned up (somewhat) + finished the euler angles/quaternion handling

- added a new little dialog in gui to specify the rotations/scales/translations by
  hand. This is similar to what I did in the Motif version of Gmsh a looooong time
  ago, and I was really missing this capability... (e.g. being able to specify
  exact rotation angles)

- the grid options now also apply to 3D views (this way we can
  finally get accurate size info for any data set; and the info
  is updated in real-time for gemeotry transformations & displacement
  maps)

- new option to specify the size of the moving axes

- generalized text align code (we now support the 9 modes that TeX
  does)

enhanced clipping planes (thick lines + easy "invert orientation")

added arrows to show the orientation of the cut plane

removed all unnecessary glPushMatrix/glPopMatrix calls

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

don' draw full stem in filled mode

fix normal orientation of second triangle

make simple arrows/pyramids look nicer when lighting is on