Added V1.3

- Added arrow sprite - player can shoot arrow at zombies
- Resized zombie and archer images so rect wasn't very oversized.
Added V1.4

- Added images so it looks like there is an animation when the player
shoots an arrow.
- Changed arrow shooting so that player can only have one arrow on
screen at a time (only shoot one arrow at a time, spamming arrow shoot
button (spacebar) will not result in more arrows being shot)
Added V1.5

- Added collision detection - player will loose health when hit by a
zombie, zombie will die when hit by an arrow.
- Game closes when player reaches 0 health