Extend the new Python Torperf to talk to tor's control port
After finishing #3281 (closed), we should extend Torperf to talk to the control ports of the tor processes it started before. Torperf should use TorCtl for this task similar to
entrycons.py. In fact, we can probably re-use most of the code from these two files.
Connecting to tor's control port has two purposes that have to be performed by the new Torperf: First, Torperf may have to influence tor's guard node selection algorithm depending on its configuration, and second, Torperf will have to process control port events and write them to a local .extradata file.
Assigning to tomb upon request.