Calibre 9.6 adds cards-based search, word-prefix matching and security fixes

Calibre 9.6 introduces a cards-based full text search view showing book covers and adds a word-prefix completion mode for more flexible searching. This release also fixes two security issues, disallowing internet background images in the e-book viewer and restricting resource files in TXT input. Users can further customize bookshelves with a new constant height option per group. Additional bug fixes and new or improved news sources are included.