swap32() and swap16() return void.

or (new) little-endian binary.  Good for Toshi's constellation figures,
which are in little-endian binary format.

MacOS X port, "home" command/button, lots of bug fixes -- into main branch!

Where appropriate, update references to geomview license too,
now called COPYING.geomview.

Once we pick a license this might change, but
in the mean time, at least the NCSA UIUC origin is noted.

Use config.h's WORDS_BIGENDIAN.

Lots of changes to support new time flow and additional
time-related GUI.  Probably not all there but at least somewhat usable.

We're little-endian if WORDS_BIGENDIAN is defined (in config.h) and set to 0,
so use #if rather than #ifdef to test endian-ness.