On Fedora/RHEL, NetworkManager.service needs to be started before
network.service, or else network.service may try to bring up NM's
devices itself.

Lennart sez:

"Oh, I wasn't aware it is short-lived only. In that case, drop the
multi-user.target bit, and just make it create the dbus alias.

[Install]
Alias=dbus-org.freedesktop.nm-dispatcher.service

And yeah, adding Also=NetworkManager-dispatcher.service to
NetworkManager.service certainly would be a good idea."

The previous ignore-carrier rules did not work well with dynamic IP
(dhcp/slaac) connections. Change the rule so that only static IP
connections can be activated when carrier is not present (but both
static and dynamic connections will remain up when carrier is lost).

Now we actually change configuration, explain that better.

The latter should have the full+canonical description, and the config
file comments should be very brief, and link to it for more info.

This is covered in the manpage adequately, and we want this file to be
actual options now, not just commented out ones.

Add a "monitor-connection-files" config option, which can be set to
"false" to disable automatic reloading of connections on file change.

To go with this, add a new ReloadConnections method on
o.fd.NM.Settings that can be used to manually reload connections, and
add an nm-cli command to call it.

systemd's new network-online target abstracts the "wait until
networking is up" stuff, and NM-wait-online implements that
functionality.  Thus NM-wait-online should be ordered before
(and thus be a dependency of) network-online.