NFD

Currently, when an Interest carrying forwarding hint reaches a default-free router, the FIB lookup procedure (Strategy::lookupFib) decides which delegation name would be used, and the strategy only has the authority of choosing which nexthop(s) to use within the FIB entry belong to that delegation name.
The strategy should be allowed to choose which delegation name as well.

Specifically:

1. The FIB lookup procedure should return a list of nexthops. Each nexthop is accompanied by one or more delegation names.
2. The strategy chooses which nexthop(s) to use.
3. The forwarding hint in the outgoing Interest to a nexthop is reduced to have only the delegation name(s) available at that nexthop.

For example, given incoming Interest /A hint={/ucla,/telia,/csu}, the FIB may return (nexthop=300,delegations={/ucla}),(nexthop=301,delegations={/ucla,/csu}),(nexthop=302,delegations={/csu}). Suppose the strategy decides to forward the Interest to face 300 and 301, the outgoing Interests would be /A hint={/ucla} and /A hint={/ucla,/csu} respectively.