Add support for SERVER_TIMEOUT SDO

[hnez]

There is a new SDO endpoint SERVER_TIMEOUT_SDO (0x2d06) that, when set to 1 enables a watchdog mode in the node firmware. When enabled the node will reset its node_id after not being pinged for some time, so that it can be re-discovered via LSS.

I would go about implementing this feature like this:

• Break out the discovery of supported SDOs from LxaNode::get_info() into a separate method (maybe also cache the results)
• Check the supported SDOs early in the node discovery
• Enable SERVER_TIMEOUT for nodes that support it as early in the node discovery as possible

[SmithChart]

During firmware development we have decided that the watchdog should default to always on. So we do not need to change any behavior in the server component.

I will add the watchdog-diable to the commandline-use documentation for the products. I'll leave this issue open to track that change.

[hnez]

It looks to me like the documentation changes are now online. I will close this issue now.