Aggregate calendars

[WhyNotHugo]

I'd like to share my calendar(s) with a few people. However, I have several (personal, work, study, etc).

I'd like to share them all as a single URL (maybe /path/to/calendars/*?) (because, honestly, someone else wouldn't care about which calendar I put stuff in).
I don't think this is a standard CalDAV feature, but I'd still love to see something like this on radicale.

This would be extra useful after fixing issue #34, since it'd be extra-useful to share all my calendars' free-busy as a single link.

Would something like this be doable? Would it be acceptable (since it's defined in any standard really)?

[liZe]

As explained in #429, adding a hook seems to be a good way to do this.