Organisation, Moving, and Combat

Organisation
+ I put different assets into appropriately named folders.

Shooting
+ The Destroyable script sets hit points for the object
+ Objects at 0 hit points will be destroyed
+ ShootBullet sets the damage that bullets do
+ Added shooting sound capability (it has a stand-in sound now)
+ Added muzzle flash

Crouching
+ Player no longer has to hold the crouch button to keep crouching
+ Fixed the gun squishing bug

Walking
+ Re-added walking sounds (it has a stand-in sound now)