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.

  - supply strcasecmp
  - not supply HUGE
etc.  So make sure HUGE, M_PI, M_LN10 are defined,
along with a few more libm functions used in kira_parti.cc.

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

doesn't already have one.

Add rint() function.