-created ShipyardNotHere for Planets with too low a TechLevel (tested
and working)
-created Shipyard (needs lots more work)
-All planets can access one of these based upon techLevel (tested and
working)
-made new method for MainCotroller: returns the object of the Planet
player is currently on
-Planet now has override methods for .equals() and .hashCode() comparing
only their String names