Add class name entry to CoordSys information window
Add solarSystem flag property accessor for Squirrel
Add orbitCenter and orbiters properties to OrbitCS for Squirrel

orbitCenter can be either an OrbitCS or an Astrobj.  You can check it
by instanceof operator.
Make materialized solar systems can have multiple planets

The naming convention for those planets should have some rules, although
currently they are assigned randomly from a, b, ... and so on.
Add solarmenu to show a window to inspect solar system structure