Add PHPx groups

[heiglandreas]

See php/web-php#1160 for more details

[inxilpro]

I have a REST API for accessing events, but I've been meaning to publish an ical feed as well. I assume it's easier for you to consume an ical feed?

[heiglandreas]

That's the already existing process so there'd not be the need to create something separate. And it'd allow attendees of the groul to subscribe to the events via their calendar 😉

[heiglandreas]

And it could be the same REST endpoint, just called with a different Accept-Header 😁