Baseball bats, pistols, and shotguns .. Oh My!

Added constants to support item types and ammo pickup counts
Refactored constant import in game.coffee and gameState.coffee
Added items field and support methods to GameState
Imported more constants in player.coffee
Added weapons and ammo fields to Player
Added item interactions to Player
Added arena item rendering to the gui
Added weapon possession and ammo count to the gui's status window
Created Item class in item.coffee to organize items