Add printinfo method to Moon and Moonlet
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.
Add kwargs to StarSystem

Add the following keyword arguments to StarSystem:

 - opencluster = True or False
 - numstars = 1, 2 or 3
 - age = number > 0

The arguments are not checked for validity, the caller has to verify
them by himself.
Merge branch 'kwargs'
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.
Add Moon and Moonlet generation for GasGiant
Fix minor errors in Moon and Moonlet
Fix bug with epistellar gas giant arrangements

In some cases epistellar arrangements did not result in complete
generation of orbits around the star as the first orbit was not deemed
valid. This case has now been isolated and fixed.
Make barebones package layout

The package layout will be as follows:

The overall package is called gurps and it contains a subpackage space,
which will house the modules for the space system generation.
Move modules into package

Move the modules into the package gurps.space and change all import
statements to relative imports.

Close #11
Merge branch 'correct-packaging'

With this merge we start to adopt a classical pythonic package
structure, which should, in theory, help us later on when trying to
ship the code.
Add example python script

Add an example script that generates a StarSystem.
Fix #12
Merge branch 'fix-bug12'
Add getters to Star

Add several getX methods to the Star class.
Change initializer of PlanetSystem

Change the init method of PlanetSystem so that it only needs one
argument: the parent star. All values needed for the next steps are
then queried from the parent star.
Pass primary star to init methods of orbit contents

GasGiants, Moons and Planets will now store their primary star. In the
future this will be utilized to check the luminosity of the star, which
in turn may help decide between some world types.