Implementation of the Keep Alive thread in the transport service.

[LePailleurThibault]

[sgunes-wirepas]

Maybe a more general question, but why is the timezone offset needed in the keepalive messages? In locations with daylight saving time, the offset from UTC would change throughout the year.

[LePailleurThibault]

These messages will be used for example in the dlms app where the application might update the connected meter local time with the UTC time + timezone offset. But, that's a good point, I will change the timezone offset input to a timezone name, so that the module will handle daylight saving time changes.