RE: Activity Proposal Review

James, Karen, Evain,

I think that renaming Action.performedBy to Action.actor are ok. Even
though Event.actor is currently defined to be an actor in a theater show,
Action does not inherit from Event, so .actor can have a new meaning. If
Action ends up extending Event, like some have suggested, its still ok that
the property's semantic is made more strict. Alternatively, Event.actor
should probably move down to the TheaterEvent type.

-Yaar