Added and fixed quite a bit this time.

Adjusted the lighting.
Weapons now shake the screen when firing.
-The amount of shaking is relative to the weapon.
Tweaked the tutorial level.
Completly redid the second level.
Zombie spawning logic changed.
Background has more detail.
Added hidden areas.
New rocky area with destroyable rocks.
-Zombies can also break these.
Destroyable crates that contain ammo.
Pistol, Assualt Rifle, and Crossbow ammo boxes give less, but have a higher chance of appearing.
Fixed a glitch that allowed zombies to fall through floors.
Fixed a glitch where if the player said no to moving to the next area the window would continousily popup as long as they were in the door.