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Changes:
* All internal PDF processing is now done with PyMuPDF. The PyPDF dependency
has been removed.
* The program now uses PyMuPDF for all internal PDF processing instead of
PyPDF. The PyPDF dependency has been removed, and PyMuPDF is a required
depencency.
* The PyMuPDF program is much stricter about setting page boxes than PyPDF, in
order to avoid inconsistent situations. Setting the MediaBox automatically
resets all the other boxes (CropBox, etc.) to their defaults. The MediaBox
is always set first. By default crops still set the MediaBox and CropBox,
but the other boxes will be reset.
* All the other boxes must be completely contained in the MediaBox to be set.
If not (when using the ``--boxesToSet`` option) a warning will be issued and
the action will be ignored.
* The ArtBox can no longer be used to save restore information. The restore
information is instead saved in the XML metadata. Documents that were
cropped by earlier versions will automatically have their ArtBox data
transferred to XML restore metadata unless the ``--noundosave`` option is
used.
* The options ``--docCatBlacklist`` and ``--docCatWhitelist`` have been removed
since PyMuPDF automatically retains the full document catalog.