To avoid all sorts of problems, we need to ensure cards scheduled with
the V2 scheduler are not studied in older clients. Unfortunately we
can't just bump the file's schema version, as the existing clients will
freely import files created with newer versions. This patch changes
that, so things should be a bit easier in the future.
In the mean time, we need a way to prevent older clients from importing
files created with the V2 scheduler. To do this, we switch to using a
'collection.anki21' file in the archive, and include a dummy collection
.anki2 file.
The code has been tested with both deck and collection packages, but
exporting deck packages w/ scheduling info will remain disabled until
the V2 scheduler has had more testing.
- always store media references in fields in NFC form
- always encode filenames on disk in NFC form on machines other than macs
- use relevant encoding when placing files in the media folder during syncs
and apkg imports as well
- rename 'unused media' back to 'check media'
- check media can now automatically change media references and filename
encodings to the correct format
