[devhelp] (4 commits) Non-fast-forward update to branch wip/swilmet/misc-improvements

[Sébastien Wilmet <swilmet src gnome org>]

The branch 'wip/swilmet/misc-improvements' 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:

  aa205ab... book-tree: remove useless #includes
  198bf78... book: better document instance variables
  e01dee0... book: deprecate unused comparison functions

Commits added to the branch:

  e27310b... Remove some useless #includes
  dc2c1de... book: better document instance variables
  d30b481... book: deprecate unused comparison functions
  4aa9bb0... book-manager: connect to DhBook signals with g_signal_conne