Fix reflow command not working

Due to changed load order and dependency on howl.app.
Add section on clipboard history (paste..)
Update Changelog
Add GtkWidget in_destruction property
Update manual images for buffer-{grep, structure}

To show off the highlighting of matches.
Readline focus grabbing part 2 - problem upon exiting app

Trying to grab focus during shutdown results in Gtk errors
spewn all over the console. Hide the readline before invoking
handler to avoid this.