remove fixed bugs, add couple new ones

there are still annoying bigs with ellipses. pfff.

missing CIRC_INV/ELLI_INV cases all over the place

consolidate all multi-entity selection routines into a single routine

slightly modified gui for transformations so that we can transform several
entities at once

when we delete the curve num, also delete the curve -num (otherwise the
control points cannot be removed, since there are still attached to the
-num curve )

add missing sanity check in interpolateUBS

trying to fix bug when one transforms a point *after* a curve based on this
point has been created (missing End_Curve())

trying to fix pb when transforming surfaces with negative curves in the
line loop

- new button under the graphic window to temporarily disable mouse
  selection (speeds-up redrawing of very large models + permits to
  rotate/zoom-in a model in selection mode even when the whole screen
  is full of selectable entities--e.g. a surface mesh)

- new "lasso" selection mode (to select entities using the same kind
  of lasso as the lasso zoom: just Ctrl+click, then drag the mouse in
  selection mode; the shortcuts are the same as for the lasso zoom)

- it is now possible to unselect entities using the middle mouse button
  (only for the creation of physicals at the moment; not sure if it's
  useful in the other cases)

- new button in visibility browser to invert the current selection
  (very useful e.g. when multiple physical entities are associated
  with a given elementary entity, in order to "peel" away the model
  when adding new physicals; cf. philou)

- changed meaning of Escape shortcut (cancel lasso or toggle mouse
  selection) + restore standard fltk Escape handling for all dialog
  windows

- updated copyright string

- new mesh label mode (coordinates); all label types are now also
  available for mesh vertices

- added option in 'Print Option' dialog to disable printing of help
  strings

- added a comment string with the date when creating a new file

- new snapping grid for adding points in the GUI

- new button under the graphic window to temporarily disable mouse
  selection (speeds-up redrawing of very large models + permits to
  rotate/zoom-in a model in selection mode even when the whole screen
  is full of selectable entities--e.g. a surface mesh)

- new "lasso" selection mode (to select entities using the same kind
  of lasso as the lasso zoom: just Ctrl+click, then drag the mouse in
  selection mode; the shortcuts are the same as for the lasso zoom)

- it is now possible to unselect entities using the middle mouse button
  (only for the creation of physicals at the moment; not sure if it's
  useful in the other cases)

- new button in visibility browser to invert the current selection
  (very useful e.g. when multiple physical entities are associated
  with a given elementary entity, in order to "peel" away the model
  when adding new physicals; cf. philou)

- changed meaning of Escape shortcut (cancel lasso or toggle mouse
  selection) + restore standard fltk Escape handling for all dialog
  windows

- updated copyright string

- new mesh label mode (coordinates); all label types are now also
  available for mesh vertices

- added option in 'Print Option' dialog to disable printing of help
  strings

- added a comment string with the date when creating a new file

- new snapping grid for adding points in the GUI

Removed all compile-time depdencies on byte ordering (big- or little-
endianness). Replaced them with run-time conversions where necessary (only
for packing/unpacking of colors into unsigned ints). Performance hit
should be negligeable, but this will allow to compile Universal Binaries
on Mac in a single step (instead of having to compile the PPC/big-endian
and the i386/little-endian separately, which wouls be a royal pain in the
butt).

change default browser on non-Win/Mac to firefox

print external and direct msgs in blue

forgot scaling

added radial gradient ;-)

don't print the stupid category headers if in 'diff' mode

upgrade to latset gl2ps

better z-clipping planes for perspective proj (should also work for objects
far off the z=0 plane now)

make depend

InitRenderModel should be called before InitPosition (to have fixed
light positions)

added small slider window to choose the z-clipping factor in real time.

FLTK is really awesome :-)

better perspective projection handling (around cog+new icon in gui)