Supervisor modes

I changed operations so that it can be applied to replicated nodes, including bind, read, next, wait_needed, is_det, declare. There are still two operations 'fetch'  and 'reply_fetch' to be done. They are used to fetch values when a dataflow variable is bound to another.
As I see now all the commands come from FSM and derflow_vnode will not spawn new commands (and they are all actually asynchronous), seems it is not possible to create deadlock in this case. Correct me if I am wrong :S.