Christopher Davis authored Sep 07, 2021 and Alice Mikhaylenko committed Sep 23, 2021

These properties are largely unused, and the defaults are
sensible. The *-unfolded properties can be replaced by using GtkSizeGroup.

Leave a single `homogeneous` property for folded+opposite orientation.

Remove `interpolate-size`, always enable it when `homogeneous` is false.
Apply it to mode transitions as well.

Closes #74
Closes #75