Port routes tests to new model
Mark as primary the first instance of subnet + tests
In preparation for subnet failover, mark the initial occurrence of a subnet as the primary one.
This commit rewrites the `routes list` command to use ptables to present
a slightly nicer list, including a new field if the route is enabled or
not (which is quite useful).
In addition, it reworks the enable command to support enabling multiple
routes (not only one route as per removed TODO). This allows users to
actually take advantage of exit-nodes and subnet relays.
tests for that feature.
Other fixes: clean up a few typos in comments. Fix a bug that caused the
tests to run four times each. Be more consistent in the use of log
rather than fmt to print errors and notices.
