Feature request: Custom repeat interval

[mhanuszh]

Personally, I have an bi-monthly expense, but a generic, customizable repeat interval would be great.

There could be a group of absolute values:
Every x days/weeks/months/years

And a group of relatives:
Every x-th day/week/month of every week/month/year

[nlogozzo]

I guess it's time for something like this: #8 (comment)