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.
Don't compare values this way, use pattern matching instead.  For instance:

```
case V#dv.value of
   NewValue ->
     %% The same
   _ ->
     %% Not the same
end.
```