Enhancement/wieldable decouple

[brian-holsters]

fixes #150

[Phazorknight]

Requested a change to Throwables defaulting to the pickup scene as the projectile. otherwise this looks solid.

[Phazorknight]

Projectile spawning:
I would not default to the projectile prefab being the same as the pickup item.
I can see cases where devs might want a the spawned projectile be a different scene than the pickup-item
(items which thrown state would differ from their pickup item state, something like armed grenades for example).

[brian-holsters]

solved by adding an optional export to the wieldable script, here's a video of it working:

https://streamable.com/i9i99n

[Phazorknight]

Thanks! That's a very nice solution.