make depend

new plugin ExtractElements to extract elements whose values are comprised
in some interval

many fixes in ReadImg (non-square images now work; no default resize; no
default scale change, etc.)

- added little routine to save a post-pro view as a mesh file
- moved all post-pro I/O routines in a separate file

reorder 2D algo menu to match #define numbers (dave)

don't draw mesh nodes by default

make sure entities appear only ONCE in the selection list.

(In order to do this without borking "undo", we have to use
linear searches. So this is slow but it seems to be acceptable
with 5000 entities. If it's really too slow, I will change it
to elimitate duplicates at the end of the selection process.)

opt to shade plane in bbox

fix Progression to actually do what we claim in the doc (missing -1 in
the formula: confusion between num_points and num_intervals)

disable lasso selection when in "Mouse selection OFF" mode. This makes
more sense.

add (undocumented) shortcut to disable nouse hovering (speeds up drawing
while still allowing to select by clicking)

fix bunch of gcc4 warnings

only recompute bbox when the geometry might actually have changed

add tests to completely bypass vertex array drawing if nothing has to be
drawn anyway

fixed ugly extrusion syntax (finally!)

extrusions are now specified in the same way as all other transformations
(the old syntax is still available, but is deprecated)

mini fixes + pretty print

rewrote the smooth normal routines:

- the averaging is now done by clusters, which is much better for
  geometries that have sharp edges  (it's a little slower, but the
  visual results are much better)
- there is now only a single smooth normal container in the mesh
  (instead of one per surface)

add little button to add param name for entity in vis browser + refresh
vis browser after adding new entities