Is your feature request related to a problem? Please describe.
As far as I can tell, the undoer API provides a publicly-constructible Settings struct, but unless I'm missing something, there is no way to actually create an Undoer using it.

Describe the solution you'd like
An API that allows you to create an Undoer with given settings, something like Undoer::with_settings(...) or a builder API for Settings.

Describe alternatives you've considered
N/A

Additional context
Does the API exist somewhere and I'm just not finding it?