Avoid unnecessary string formatting
Make ads in user manual async
Ensure we dont leak a file handle
Fix test failures due to file locking on windows
Initial implementation of add_format()
Fix detection of SD Card in some PRS-T2N devices

Fixes #1197970 [Sony PRS-T2 SD card not recognized](https://bugs.launchpad.net/calibre/+bug/1197970)
version 0.9.38
Add tests for add_format()
...
Implement remove_formats()
Clarify use of OPF in calibredb set_metadata
Implement create_book_entry(), with tests
Metadata download dialog: Have the OK button enabled in the results
screen as well. See #1198288
...
Implement add_books()
Initial implementation of remove_book(), needs testing
DOCX Input: Fix no page break being inserted before the last section.

Fixes #1198414 [Private bug](https://bugs.launchpad.net/calibre/+bug/1198414)
Glenn Brenwald and Ludwig von Mises Institute by anywho
Tests for remove_books()
Test emptying db