[devhelp] (4 commits) Non-fast-forward update to branch wip/book-list

[Sébastien Wilmet <swilmet src gnome org>]

The branch 'wip/book-list' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  e50bf25... BookManager: remove all the implementation
  5395369... Preferences: port to DhBookList
  c4d35ee... Preferences: listen to the DhSettings::books-disabled-chang

Commits added to the branch:

  74ace33... Settings: better document the ::books-disabled-changed sign (*)
  6e268b9... Settings: add freeze/thaw_books_disabled_changed() (*)
  7b5095d... Preferences: port to DhBookList
  08fa62c... Preferences: listen to the DhSettings::books-disabled-chang

(*) This commit already existed in another branch; no separate mail sent