- changed UNV output to match MSH output w.r.t. physical groups
- new UNV file reader

add CBAR for lines in BDF

make clear that we only read/write "free format" BDF files, with a comma as
the separator symbol

make sure we store all types of elements

make all dialog windows resize correctly with the font size

use MSH version 2 by default

Added support (both read and write) for the Nastran Bulk Data File
format (BDF).

This might need some adjustments depending on what the actual spec
is: I just reverse engineered some BDF files I found on the web :-)

refer to .mesh as MEDIT format, not INRIA format

store partition number as a short (instead of a full integer)

set the 2 padding bytes in binary STL to 0 (it's just cleaner)

missing activate_cb string for general transformation button

put fltk popup bug fix in a single header file

draw the rotation center

default tensor type should be 1

fltk does not like the KEYUP thing -- reverting to KEYBOARD

- test <hash_map> (commented out for now)
- added "box" mode to clipping planes GUI

couple more when(FL_RELEASE)

better fix: the window can exist and take events even BEFORE it has been
"updated" for the first time

fix crash

more when(FL_RELEASE) on expenive callbacks

for some of the expensive options, set when(FL_RELEASE). We'll see if we
need to add more later

do_callback() on KEYUP

only do_callback() on release

Options in the GUI are now applied instantenuously.

Please let me know if you see anything weird in the GUI.

- better computation of bounds for discrete entities
- added small widget for light position selection
- infrastructure for Fourier models

much better selection of center of rotation (can select ANY entity now to
prescribe rotation center)

better rgb/hsv conversion