A small hack to retrieve new entries in the registry and format them into
an atom feed as well as microblog services.

Currently, this posts to Mastodon.  This needs credentials in
fed_creds.txt.  To obtain them, log into the https://fediscience.org
go to Preferences -> Development, New application.  Leave the redirect
URL as it is (you only need that browser-based stuff). fed_creds needs
client_secret, access_token, api_base_url, one per line, keys separated
from values with blanks.

We memorise what we've already published in the sentOut table.  These
guys never get re-tweeted or into the RSS (this used to be different, where
we'd re-advertise modified resources after two years or so; this proved
to be confusing to users).

If re-starting this service, you can seed this table from the current registry
content if you have a relational registry running.  Just say
python bin/seed_setout.py.

We also bridge this to bluesky; see https://fed.brid.gy/docs for how to
set this up after another server move.