Spawned Entities need a reference to their SpawnPointComponent

[dmlary]

When an entity is removed from the world, and it has been Spawned, we need to update the origin SpawnPointComponent so a new one will spawn.

Likely need to add a SpawnedComponent, with an origin field that is a ref to the SpawnPointComponent.

[dmlary]

# Note that the Entity came from a SpawnPoint.  When this Entity is removed
# from the World, the active count in the corresponding SpawnPointComponent
# must be decremented.
#
# Aww FUCK.  I think this is the moment where we have to move
# SpawnPointComponents out of the Room Entity.  A Room may have multiple
# SpawnPointComponents.  We can only reference an Entity within a Component.
# How do we make this SpawnedComponent point at a specific Component within the
# Entity?