Push images via ZMQ

[tfarago]

Rationale

So far I have come up with this based on the dicussion here, summary:

• it merely adds handle_push_request to ucad and re-uses the rest for control of the cameras (I don't see the necessity for a completely new ucad-zmq server)
• it removes the zmq pushing from the camera class itself because it doesn't belong there
• it enables to use it from concert via camera = Camera('net') for control
• it enables us to have native async-based camera.grab_push(), which can be added as a mixin or whatever else extension of the python camera object
• one can specify how many frames will be grabbed & pushed to remove communication overhead

Use case

[matze]

Cool, much better!

[matze]

By the way, are you going to do some benchmarking? I mean just pushing via ZMQ does not make packets fly magically faster over the wire.

[tfarago]

Of course I will. And sure, I don't expect zmq to be much faster. The point is rather that from python I can tell the server to stuff the images down the wire without actually needing to touch them in python. So far, on my laptop I get 4 GB/s with zmq and 5 GB/s with your streams, but I use python to receive the zmq which also slows things down I guess. I will make all kinds of tests later and example experiments in concert.