- Added OnTriggerEnter() function to PlayerController.cs.
 - Added Pickup tag, and assigned it to the PickUp prefab.
 - Set PickUp prefab collider IsTrigger
 - Added RigidBody component to PickUp prefab.
 - Checked IsKinematic checkbox in RigidBody component.
Merge branch 'feature/06_CollectingAndCounting' into develop