Small fixes for old fltk versions (1.0)

Save more window positions + polish previous commit (restore defaults)

Major GUI overhaul. All options are now available in a single
window.

Add ability to draw lines as 3D cylinders. Looks very nice with our
stream lines :-)

Finally! Synchronized my laptop with office machine.  Use black and
white version of the Windows/Mac icon instead of the old 'gmsh'
script. Should scale better with Gnome/KDE. Back to real work now.

Introduce OpenGL display lists for drawing meshes. Does not seem to
work much faster on my machine, though.

right-clicking on the view button (which nobody found without asking
me... and was not easily available on Macs with 1 button mice), there
is now a small arrow (with a tooltip) next to the view
button. Clicking on this arrow pops up the option menu.

- "OK" is to agree with what in the dialog *AND* close the dialog
- "Apply" is to apply the current values selected in the dialog, but
   leave the dialog open
- "Cancel" is to close (hide) the dialog and *NOT* apply the
   changes that might have been made in the dialog

Also increased default width of buttons

Fix make source

Simplify error messages in parser a bit and change msg from ERROR to WARNING for list of shapes (less annoying when doing generic transformations, e.g. of points). Noticed this thanks to Genot Jean-Sebastien <JSGenot@HerouxDevtek.com>

Msg) firing a 2nd draw() before the fir(st has finished... This is a
general problem with our "pseudo-threaded" (i.e. putting many
WID->check() calls) approach... I added a new lock in draw() (we
already have one in Generate()), but this is pretty ugly.