Add nextGauss() method to RandomSequencePtr for Squirrel
Add RandomSequencePtr argument to materializeStar in Squirrel script

Now the Squirrel version of materializeStar is as capable as native
code.
Avoid zero division in corner cases in checkEclipse()
Change signature of OrbitCS::orbit to accept Barycenter also
Make Barycenter constructor accessible from Squirrel scripts
Make Barycenter::updateInt accept non-Astrobj orbiters
Fix two-body problem computing in Barycenter with circular orbit
Make OrbitCS around binary star behaves more naturally

The OrbitCS orbits around barycenter of binary stars with angular
velocity calculated by sum of the stars' mass.
Make randomly generated stars materialize occasinally as binary stars