Fixed a bug whereby GameStates would be drawn in the wrong order.
Added a method to empty the Inventory.
Added a respawn method to Player to handle respawning after death: includes resetting the hull and emptying the inventory.
Fixed a build error due to an erroneous "const" declaration on a function signature.
Fixed errors in the Player::respawn() method.
Added a DeadGameState to represent the game behaviour when the player dies. The state is pushed onto the stack by the MainGameState. The player presses a button to respawn, and then the DeadGameState calls the appropriate functions and then marks itself dead.