network-list: Make this a sorted list

network-list: Make this a sorted list

The list is now organised so that it is always ordered.

This allows us to find if a network is on the list a lot
quicker using binary search as well as inserting a new
network at the right place.

This will benefit loc_network_exclude with very large networks.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>