In the past we used suppress_from_homepage, it had mixed semantics
it would remove from category list if category list was on home and
unconditionally remove from latest.
New setting explicitly only removes from latest list but leaves the
category list alond
* Split alias levels in mentionable and messageable levels.
* Fixed some tests.
* Set messageable level to everyone by default.
* By defaults, groups are not mentionable or messageable.
* Made staff groups messageable by the system.
My discourse instance will be making regular automated public backups
of specific categories. It's preferred to be able to directly control
the path and filename of the output, rather than letting discourse
choose for me. This was already mostly supported, a filename parameter
just needed to be passed through the cli app.