Ebookconverter

- fix OpenGraph URLs in html5
- allow cover jobs for non-text texts (audio, data, etc.)

- Change Facebook graph API version to 19.0. No changes affect us.
- update_from_backup_workflow changed to update_from_workflow to add pubinfo from json files made before version 0.7.0 was turned on (~ August 2021)
- ReparseCredits looks at books without credits and checks to see if parsing the pg header helps.
- update libgutenberg to 0.10.24, fixes author ordering

- fix bad error handling in FileInfo
- don't save new credit unless it's new
- libgutenberg 0.10.22
- fixes bugs that resulted in duplicate credits
- fixes a problem that scraped credits overwrote the changes from json file

- credits should be changed, not appended. Fixes 35.
- added a script to remove extraneous credits
- Ebookmaker 0.12.40, libgutenberg 0.10.20

- fix RDFWriter to include the DCMIType ('Text') for books. It does not appear that this ever was done since the advent of EbookConverter. Fixes 42.
- Ebookmaker 0.12.37

- removed the `.utf8` extension from txt, html, and rst generated files