I've reviewed your patch, and made a few changes:

- reverted the changes to dns_view_addnewzones(), put the allow code back
  into view.c.
- moved your file_sanitize_legacy() function into view.c as nz_legacy()
- made new-zones-directory a view option instead of options-only
- added a dns_view_setnewzonedir() function. That's now used by nz_legacy()
  to find the right place to put the files
- added documentation of new-zones-directory
- noticed that the existing documentation of NZD and NZF files was rather
  poor, so expanded them
- fixed the test to check for NZD instead of NZF when linked with LMDB

(I want to thank you for writing a test, that was particularly helpful.)

Since I changed your code a fair bit I'm going to ask one of my colleagues
to review it too, but I expect this will be merged to our master branch (for
9.12.0) soon.

Thank you again for the contribution.