Release 1.9

OS updates, including fixes for recent OpenSSL vulnerabilities. Kernel updated to 4.1.13.

Improved device support: * Corrigo Ventilation Killswitch * Support more registers & programs in Corrigo Ventilation Controls * Improved multi-message mbus meters * Multi-threaded modbus reading * Corrigo Heating support for Heating System 2, Differential Pressure and more * On device network statistics * Further deprecation of Python2 code