finer control of time/timestep display

New plugin to compute the modulus and the phase of a complex-valued field
in-place, in one simple step. One could already do this with Plugin(Evaluate),
but it was a little bit cumbersome.

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.

reorder

removed remaining Discrete Line/Surface stuff

added small warning in automatically generated opt_* files

better help string for '-combine'

added all the missing "Combine" modes in the parser

doc 2nd order elements

- Generalized the "View" parser so that we can add new elements more easily
  (the code is *much* shorter, but unfortunately about 10-15% slower)

- Upgraded all post-pro file formats to handle curved (second order)
  elements: SL2, VL2, TL2, ST2, VT2, ... The new version number for the
  postpro files is 1.4

- Added code to automatically split the curved elements into linear
  elements when the view is created. WARNING: this is only a temporary
  solution: weshould generalize Adaptive_Post_View to handle these curved
  elements.

add line stippling for 2d plots

removed unused Post.Scales option

small doc fix

new option to control a view's axes color

treat quads in poly_rep_to_mesh: this way we can also extrude discrete
surfaces meshed with quads

- fixed double free in case there is an error in tSprintf

- new StrRelative command

- small demo on how one can add a generic title to a plot using
  Plugin(Annotate)

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)

change sign of levelset so that the iso-volume is more natural

Plugin(Extract) can now also extract data from a specific time step

Generalized Plugin(Extract) so that it can also create tensor views

small generalization: we can now interpolate data from abritrary
views (and not only from views having the same data type as the
destination)

I use this to interpolate (combination of) components of a field
in one mesh onto another mesh, for example a set of isosurfaces
from another field. Wicked cool! ;-)

small doc fixes

- generalized the octree code to make it work with all the element
types, and not only with triangles/tets (and fixed a couple of copy &
paste bugs in the process...)

- modified all depending plugins to take advantage of this

change the behavior of "-string string" command line option to match the
bahavior of "-option file"

- 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