allow nested facsimile elements

[martinascholger]

This PR addresses #2565

[martindholmes]

After some discussion with @martinascholger, we decided that this approach is too loose, and allows lots of weird content mixes (facsimiles interleaved with surfaces, for instance) whose meaning is hard to fathom. The feature request is just for the ability to create a facsimile containing child facsimiles, so perhaps the content model should just be an alternate between the existing content model and one or more facsimiles.

[tuurma]

@martinascholger @martindholmes I agree with the proposed alternate - either nested facsimiles or surfaces etc

[sydb]

Just to be sure I understand, y’all are proposing

facsimile = ( model.graphicLike | surfaceGrp | surface )+ | facsimile+

as opposed to the current definition (on this ms_2565_facsimile branch) of

facsimile = ( model.graphicLike | surfaceGrp | surface | facsimile )+

Right? If that’s the case, seems like a good idea to me, but I would want to hear from the likes of @MatijaOgrin, @jamescummings, or @schassan before merging into dev.