Init the controller, optionally passing a controller
command table.
| aCommandTable | a command table, used internally by this controller. May be null, in which case the controller will create a new, empty table. |
Set a context on this controller, which is passed
to commands to give them some context when they execute.
| aCommandContext | the context passed to commands. Note that this is *not* addreffed by the controller, and so needs to outlive it, or be nulled out. |