Refactored migrations to reduce redundancy.
Migration for item ISBNs/codes to editions.
Updated ISBN search to use editions instead of items.
Fixed bug in SQL (wrong field name).
Restored display of product codes / ISBNs.
Fixed editing of ISBNs / product codes.
Removed unused code/tables.
Added OCLC number support.
Added edition descriptions.
Merge branch 'master' into dimenovels.org