We seem to have made node_announcement propagation *worse*, not
better. Explorers don't see my nodes updates.
At least some LND nodes never send us timestamp_filter, so we are
never actually stream *any* gossip. We should send gossip about
ourselves, even if they haven't set a filter (yet).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: Protocol: we more aggressively send our own gossip, to improve propagation chances.