Squashed commit of the following:

    apps/netutils/netlib:  netlib_ipv[4|6]adaptor() will now use the new routing table interfaces if they are available:  If the desination IP address does not correspond to the network served by any device, then the address of the router that should get us to the correct sub-net is is determined.  Then the network adaptor that can communicate with the that router has the IP address that will returned.

    apps/netutils/netlib:  Add new utilities netlib_ipv[4|6]router() that can be used to determine the IP address of a router that would be used some some destination IP address that is not locally accessible.

    apps/netutils/netlib:  Add helpers for reading the routing table:  netlib_read_ipv4route() and netlib_read_ipv6route()