Aurie actormap support

This adds some initial support for Aurie on actormaps.

There are three new actormap functions this adds:

• actormap-take-portrait: This takes a snapshot or portrait of all actors in an actormap based on one or more given roots. Returned to you are two values the snapshot itself and the roots. The snapshot should be serializable if desired.
• actormap-restore: This takes in a actormap, snapshot, aurie environment, and the roots of the objects. It restores the objects with the given snapshot data in the actormap using the constructors specified in the aurenv.
• actormap-replace-behavior!: This is designed so you can "upgrade" objects to different behavior using aurie as that upgrade mechanism. You provide it two aurie environments, the first being the old aurie environment and the second being the aurie environment with all the updated behavior in. It'll diff those aurie environments to find those with new behavior and then find all objects of the found types. These will be depicted and rehydrated using the new behavior and that new rehydrated object installed at the old refr.

More on how these are used can be found in the docs or in the tests.