Recurring transactions

[fhreichert]

Is your feature request related to a problem? Please describe.
Some transactins happen on a schedule, such as payroll or monthly subscriptions.

Describe the solution you'd like
A way to mark transactions as recurring on a (custom) schedule, so they are added automatically.

Additional context
Ideally single transactions of a series can be edited in some way. E.g.: These 3 months were cheaper due to a stimulus pack, recuding the VAT.
The functionality to edit all series events in bulk is not as important as being able to edit single transactions in my opinion, as past transactions usually don't need changes.

[malfynnction]

Waiting on envelope-zero/backend#49 & envelope-zero/backend#50 for this