RADIUS with shared networks

When RADIUS was implemented, we didn't have shared networks support. As a result, there was a mechanism designed (subnet-reselect) to do something a bit similar to shared networks.

We need to look at the code and see:

• what is needed to make RADIUS work with shared network
• what the limitations would be

RADIUS has some substantial limitations as a database-like system, but the basic assumption that it can return attributes that are mapped to client classes should be viable.

#403 (closed) has a discussion about current (1.5) code and its limitations.