Implement cpppo.remote.plc general polled remote io
Get Modbus/TCP PLC simulator and unit-tests working
o Ship modbus_sim.py and install /usr/local/bin/modbus_sim script
o Make sure we wait for the modbus_sim to start up for unit tests
Clean up remote.plc... unit tests
o Import with namespace, due to use of 'plc' name in tests hiding module
o Await stoppage of remote.poller to avoid logging when simulator exits
Further cleanup of cpppo.remote
o Move cpppo.__version__ into __init__.py
o Make misc.nonblocking_command available
o remote.plc.poller.poll robustly defaults the rate for new polls
o Make remote_test.py robustly bring up modbus_sim over range of ports
o Confirm poll times respond by stress-testing the addition of many
  new polled registers
Merge branch 'feature-remote'
o Version 1.9