Merge pull request #18 from lijiaqigreat/simplegui

simple graphics
made sprite fields a little clearer
Merge pull request #19 from RoboNickBot/spritechange

made sprite fields a little clearer
initial commit of untested Game, Player, and InterfaceWithGame
SimpleTanks have access to owning player's spritelist
GAME AND PLAYER STRUCTURE TESTED AND WORKING
Merge pull request #20 from RoboNickBot/players

Game, Players, and InterfaceWithGame interface