Orbital Mechanics article and applet updated

Hi folks - 

   I finally got a bit free time, so I rewrote the orbital mechanics
article on the Exodus Project site (http://www.ExodusProject.com) and
finally (I hope!) squashed the bug in the applet.  The article is now
hopefully much easier to follow, as I've added units to all the
equations throughout and provided a summary and example for each
section.  The applet should be considerably easier to use as well.  I'd
appreciate reports of any bugs you may find in either item!

Thanks..
Keith
-- 
Univ. of Maryland Astronomy
http://www.ExodusProject.com