* Add card meta for persisting custom scheduling state
* Rename meta -> custom_data
* Enforce limits on size of custom data
Large values will slow down table scans of the cards table, and it's
easier to be strict now and possibly relax things in the future than
the opposite.
* Pack card states and customData into a single message
+ default customData to empty if it can't be parsed
Co-authored-by: Damien Elmes <gpg@ankiweb.net>
* Replace Card.data with .original_position
* Use and update original position in v3
* Show original position in card info
* Revert restoring original position for now
* Fix pb card to/from pylib card
* Try original_position as the last pb field
* minor wording tweaks (dae)