Alpha release with new REP_watcher option, DHT11 & DHT22 sensor support and more PiCamera settings

This release adds a REP_watcher yaml option that checks for a timely REP after sending a REQ, removing the dependency on signal.SIGALRM, which does not work in Python threads. It also adds DHT11 & DHT22 temperature / humidity sensor support and many more PiCamera settings. See HISTORY.md for details.

Alpha release with threaded image sending

This release adds threaded image sending as an option. That way the camera captures images and runs detectors on the main thread while image sending via imageZMQ happens on a different thread. See the send_threading setting in the Yaml settings documentation.