Implement recurring events

[markuspoerschke]

No description provided.

[alies-dev]

this is probably the most waiting feature :)

[amnuts]

@markuspoerschke, I've made a start on recurrence rule generation as it didn't seem to be done yet. It's a draft PR right now as I need to write some tests and such, but it's 3am for me so have decided to give it up for the night! 😁

Hopefully this is what you're looking for (or were a few years ago when the issue was opened!)

[amnuts]

Have added tests and tweaked some of the code, so I think it's ready for someone to give it a code review and try. Have taken the PR out of draft.