make the player actor service support commanding multiple actors

[ssube]

The player actor service currently focuses on a single actor, by actorType, for whom its commands are used. Setting multiple actor's actorTypes to player will cause them all to perform the same actions.

Extend the player actor service to support multiple actors and accept input for each in turn (in each turn), allowing multiple people to play together at the same keyboard, or one person to manage an army.