Update reference to hive to be dynamic state, simplify create-actor.

This also eliminates bootstrap-actor.

* 8sync/actors.scm (<actor>, actor-hive-channel): Removed hive-channel
slot from <actor>.
(*hive-id*, *hive-channel*): New variables.
(spawn-hive): Update to parameterize *hive-id* and *hive-channel*.
(%create-actor): No longer take hive-channel and hive-id as arguments.
(bootstrap-actor, bootstrap-actor*): Removed since these are now
unified with create-actor.
(create-actor, create-actor*): Updated to remove argument of
from-actor and update argument calls to %create-actor.
(self-destruct): Use *hive-channel* parameter.
* demos/actors/botherbotherbother.scm:
* demos/actors/robotscanner.scm:
* demos/actors/simplest-possible.scm: Update calls to create-actor and
remove bootstrap-actor references.