Basic, working production calculations

[strburst]

Note that the diff includes things changed in the shop-refactor branch (#41). You can find a clean diff here: https://github.com/MountainRange/MULE/compare/shop-refactor...production-calc. That branch has been merged; the diff is now fine.

I've added the following things:

• Working production calculations in ProductionManager
• The necessary hooks in the nextRound method of GameManager for applying production results
• Minor additions to WorldMap and Player to facilitate production calculations

For now, production calculations don't include the "economies of scale" and "learning curve" bonuses, but I'm planning to include those later if we have time.

Also, I also might add precise descriptions of the formulas used when to the Javadocs in the future, and some tests if I get the chance.

[strburst]

Oh, also, we should probably give the players normal turns for them to move around and install MULEs after giving them free land in the first three rounds (or alternatively make the free land grants an alternate phase in the game). We're actually calling endTurn, incrementing the roundCount, and calculating production for the land grant rounds, which is causing the players to be starving by the time they can do stuff on turn 4.