The same node can now be controlled by multiple synchronizers at once.
Spawn visibility is composed in OR across multiple synchronizers (i.e.
if any synchronizer is visible to the peer, the object will be spawned).
Synchronizers controlling spawned nodes can now have a different
authority then the one spawning the node, in that case, the spawn
variables for that specific synchronizer are simply ignored (other
synchronizers with the same authority of the spawner will correctly
synchronize variables on spawn).
The SceneReplicationState class has been completly removed, since it was
bloating the implementation, the state is now simply stored in the
SceneReplicationInterface.
32a62af648