Support echoing output from other clients...
Support echoing output from other clients
in the zmq console
Can result in outputs like:
```
In [1]: 1
[remote]In [1]: 1
[remote]Out[1]: 1
[remote]In [2]: 3
[remote]Out[2]: 3
Out[3]: 1
```
Note that there will be inconsistencies in prompt numbers
because some execution may take place after the in-prompt is drawn.
