New major version 1.7.6.0

Since summer time I was adding some features to gateway that led into new major version 1.7.6.0. Changes include:

• Remote zones added.
• Added group arm and disarm chain. That is when arming/disarming group by key, Gateway is able to automatically arm/disarm another group or groups.
• Added group state MQTT publish. Gateway now, if enabled, will publish state of group via MQTT. Such information can captured by Home Assistant or other automation program.
• MQTT sensor publish structure modified, added group name to path.
• Updated MQTT library and MQTT protocol to 3.1.1.
• Added new sensor type "Battery", to easily identify battery powered nodes voltage. 
• Added new sensor type "Gas", to easily identify any air quality environmental sensor.
• Added SMS command gateway. Authorized numbers from contact list are able to get Group state or set it On, Off, Arm and Disarm by sending SMS in predefine format to gateway GSM number. This functionality need some testing.
• Updated NilRTOS to latest version available. In future port is needed to ChNil, which is newer replacement of NilRTOS, but unfortunately not one to one compatible with NilRTOS.
• Various small enhancements in code and web interface.

New version is now at GItHub.