* Room creation/destruction is now separeted from starting/stopping
(creating/destroying jmcore links)
* Rooms can now be created and destryed when studio is stopped
* Rooms are started/stopped when studio is started/stopped
Apart from better interraction of studio start/stop and room
lifecycles, it is now possible to implement load of studio with rooms
because during studio load rooms have to be created in stopped state
and eventually started only at later stage, during studio start.
explicit disconnects must remove connection objects
implicit disconnects because of port disappear or external disconnect must
cause hide so when studio is stopped and then started, connections are restored.