Sam raet 18 Added support for generic Raet road and key data persistence

Raet Roads via stackUdp now persist the estate data including the long term key data.
A modular interface via the RoadKeep and SafeKeep objects allows it to be extended to other mechanisms
such as Salt's key persistence.

Stacks now have "main" parameter that changes the key status semantics of its SafeKeep object for a main stack versus not
Stack now have 'auto" parameter that changes the key status semantics of its SafeKeep Object for accepting keys