[devhelp] (16 commits) ...Call dh_book_manager_free_singleton() at the end of main()

[Sébastien Wilmet <swilmet src gnome org>]

Summary of changes:

  f717bda... BookManager: populate it in init() (*)
  9d1c601... BookManager: re-order the functions to avoid prototypes (*)
  a6f1df2... BookManager: add get_singleton() and free_singleton() (*)
  abe58e9... BookManager: deprecate new() (*)
  de15486... App: do not store the DhBookManager (*)
  def8cc6... AssistantView: remove dh_assistant_view_set_book_manager() (*)
  3d89e78... Preferences: do not store the DhBookManager (*)
  15e904a... KeywordModel: remove dh_keyword_model_set_words() (*)
  fd1457e... BookTree: remove book-manager property (*)
  2ba91ec... BookTree: move code from constructed() to init() (*)
  0c1d65b... BookTree: more precise return type for new() (*)
  09fc82a... Sidebar: remove book-manager property (*)
  813beef... Sidebar: move code from constructed() to init() (*)
  06fd9cc... Window: use dh_book_manager_get_singleton()
  60bdee1... App: remove dh_app_peek_book_manager()
  54038fe... Call dh_book_manager_free_singleton() at the end of main()

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