Add a bare-bones library for writing tuples as a .ods stream.
Refactor models.export (leaving deprecated stuff)
Refactor DocumentSetExportController to support other formats
Name exports after their titles. [finishes #58354618]
Decode path filename properly. [finishes #58354618]
Export document titles. [finishes #63750944]
Add XLSX format. [finishes #62559464]