Add Receiver API to manage Processing (abort / erase / get_states)

• Add abort_proc and erase_proc to receiver RPC interface
• Add ROI counters to the Lima1 graph (for the simulator)
• Implement receiver::get_states() that returns a processing graph state variables accessor to retrieve counters (from checkpoints), ROI counters, etc...

On a side

• Add a telnet client script to communicate with both control and receiver servers
• Update the python binding
• Fix the simulator generator (add rounding channel converter, the default one being not a good fit)