Additional rotations should be appended to the list at the bottom

[nilmerg]

Adding a new rotation to a schedule inserts it at the top of the list right now.

Goal

It should be appended at the bottom instead.

Implementation Hints

Rotations have a priority assigned to them. There should already be a way to preserve these and only re-index only what needs to. Though, adding a new rotation and keeping it at the bottom then has the expected side-effect that all rotations of this schedule need to be re-indexed.