Commented SceneController
Refactored Firearm

- Renamed randomRecoil to RandomRecoil
- Added comments
Added comments for Projectile classes
Removed the PickupCollisionHandler

- We're not currently using it, and it wasn't general enough to be useful for now.
Added comments to physics classes
Refactored the Inventory and InventoryItem classes
Moved Firearms prefabs to Player/Firearms folder

- The structure more closely matches our organization of the scripts.
Added comments to ReticleController