Log Message:
calibre: update to 3.21.0.

- version: 3.21.0
  date: 2018-04-06

  new features:
    - title: "Browser viewer: Allow showing the time left in the current \ 
chapter/book in the header and footer areas of the book."
      description: "To use go to the preferences of the browser viewer and \ 
customize the headers and footers to display the time left. Note that time left \ 
in chapter only works correctly if chapters are in separate HTML files in the \ 
book."

    - title: "Manage tags dialog: Searching now shows all matching tags and \ 
there is an undo button to undo changes."

    - title: "Add an output profile for the Kindle Oasis 2017"

  bug fixes:
    - title: "Content server: Fix adding/deleting books and editing \ 
metadata not updating the main calibre book list automatically."

    - title: "Viewer: When doing a dictionary lookup, remove soft hyphens \ 
from the word, if any are present."

    - title: "Edit metadata dialog: Fix tab order for buttons to the left \ 
of the title and author"

    - title: "Trim cover dialog: Remove the redundant Trim & OK button, \ 
instead have the OK button trim automatically if there is a selection."

    - title: "Update Amazon metadata plugin for a website change"

    - title: "Content server: Fix translations not being updated without \ 
clearing the browser cache"

    - title: "Content server: Fix switching from translations to no \ 
translations not working"

    - title: "Content server: When updating interface data do not transmit \ 
translations if they have not been changed. Saves ~30-60KB bandwidth when using \ 
non-English interface language."

- version: 3.20.0
  date: 2018-03-23

  new features:
    - title: "Content server: Allow editing the metadata of books from the \ 
book details page"
      type: major
      description: "On the book details page, you can now edit any metadata \ 
and change covers by clicking the edit metadata icon in the right area of the \ 
top bar. Note that only users that have write permissions for the library can \ 
edit metadata."

    - title: "Kobo driver: Recognize Kobo Aura 2 with new firmware \ 
(4.6.10188)"

  bug fixes:
    - title: 'When reading metadata from HTML also recognize <meta \ 
name="dc.description"> as being comments'