Create a parent class World for terrestr. planets
Compress Moon and Moonlet classes

Move the Moon and Moonlet classes into the OrbitContents module and
compress the Moonlet class (formerly subclass of Satellite) into the
new Moonlet class, incorporating the Satellite methods.
Add Moon and Moonlet generation to (terr.) Planet

Add automatic generation of Moons and Moonlets to terrestrial Planets.

Also add a getSatellites() method that returns an array of the
Satellites.
Add setOrbit method to Moon

Add a method that defines the orbital radius around a Moon's parent
planet.
Merge branch 'remodeling-world'

This branch was used to switch the Moon class from a child of the now
non-existent Satellite class to a child of World. Moonlet and Satellite
were combined into a new Moonlet class.