Pyotgw

- Fix for OpenTherm Gateway 4.2.8.1
- Change log level and message for E* messages from the gateway.

- Copy DEFAULT_STATUS instead of editing it
- Update README.md

- Avoid sending updates twice for related changes to status (22)
- Separate thermostat, boiler and otgw status (20)

- Improve connection routine
- Cleanup after unfinished connection attempt in disconnect()
- Make SerialTransport.write() non-blocking
- Add debug output to write operations
- Add Python version to setup.py (15)
- Add Travis to the repository (14)

- Send empty report on connection loss
- Fix debug output for python <3.8
- Add debug logging to watchdog
- Fix commands while not connected.
- Add pre-commit and use several linters to ensure a consistent code style (12)

- Fix iSense quirk handling bug
- Improve disconnect handling, add more debug logging.