Pickup rework

Pickups were not working very well so I spent some time reworking them.

The issues I noticed were that "dead" pickups spawned, cloth pickups that didn't do anything.

In order to resolve this two changes were made:

• Pickup spawner is now better at picking appropriate powerups
• Cloth pickups may restore health to whomever picks it up, thereby letting it act like a health pickup and therefore never becoming completely useless.