[FEATURE] Allow events to reoccur at irregular intervals.

[Galphanore]

Is your feature request related to a problem? Please describe.

Right now you can only set notes to repeat weekly, monthly, or yearly. Unfortunately...if you do this and set an event to repeat annually on a leap day, the event still repeats even on years without that day. So, for instance, if you create an event for Shieldmeet on the Harptos calendar, on non-leap years it shows up on Eleasis 1.

Describe the solution you'd like

Solution for my use case would be to allow you to set an event to repeat only when a date comes up if it's a leap day, but a more wide scale applicable use would be to have more options for how often you can repeat an event.

Additional context

Right now I've just created individual events for each of the next handful of leap days but it would be nice to do things like have an event repeat every 2 weeks or every 3 months or whatever.