ABOUT_XPM for flyingwindows

From Dr. George Ferguson <ferguson@cs.rochester.edu>, who sent me the code
for XPM support for Flying Windows:

> Bill: I picked up your flyingwindows hack for xscreensaver and loved
> it. I couldn't resist hacking it a bit to support XPM for color
> pixmaps of the BSD demon, Tux the penguin, and the Sun spaceship.
> 
> I include below a uuencoded, gzipped, tarchive of the relevant files.
> For the main flyingwindows.c file, my changes are marked with a #ifdef
> USE_XPM. In the bitmaps directory, you will find left- and
> right-facing images of the demon and of the penguin, both cropped from
> webpage gifs. I also cooked up a raytraced spaceship with the Sun logo
> image-mapped onto it. Hopefully none of these will cause copyright
> problems.
> 
> There are a few things I didn't do, or didn't do right:
>  - I didn't do was make the use of XPM dependent on the visual on
>    which the program was running. I suspect you'd get pretty horrible
>    problems if you ran it on a mono display, for example. I have a
>    TrueColor display, so this is not a problem for me.
>  - I also didn't do anything particularly smart in terms of managing
>    the X graphic contexts (GCs). It would doubtless be better to only
>    modify the GC (XSetClipRegion and the like) when the image
>    changes, rather than at every step (GC modifications require a trip
>    to the server and back).
>  - It seems that for the left-facing BSD demon, the "lines of fire"
>    don't come from the right place (too far right). No idea why this
>    would be the case, if indeed it is the case.
> 
> Well, hope you might find this useful.
