Changes:
	Turret Class: As of now, spawns with the base and rotates around it.
	Base Class: Constructor now calls a method "generateTurret()", which initializes some number of turrets to protect the base. New method, "checkBorders()", which is identical to that of Ship class.
	Obj Class: New member variable, team. I figure we'll need it at some point so we may as well add it now. We may want to consider making two new classes that derive from Obj: a player controlled class, which would include variables like "team", and an NPC class which would be for things that should be neutral like astroids and credits.

To Do:
	Add shooting functionality to turrets, which sould include things like targeting, firing, and team checking.
	Fix the bullets on the ship. They are not removed once they are out of range.
	Reduce the ship's acceleration and put a cap on acceleration.
	I still think we should re-evaluate how we check collisions. Once there are a lot of bullets and credits on the field, the game slows down a lot.
	On a related note, astroids should release credits less frequently.
	Collisions between astroids can still be a little glitchy. At some point, we need to take 30 min and mess around will good values for mass and acceleration.