More properties

What's Changed

• MINOR BREAKING Renamed BookInfo.industryIdentifier to BookInfo.industryIdentifiers
• NEW Added the following properties to BookInfo:
  • .subtitle, .previewLink, .infoLink and .canonicalVolumeLink
• NEW Added Book.saleInfo
• NEW Implemented equality in all classes

New Contributors

• @niklasenberg made their first contribution in #13

Full Changelog: 4.2.0...4.3.0