Fix key "Page_Down" identified as "Next"

Since 49c4ad2f the order between "Page_Down" & "Next" had been changed (due to
sorting) and this resulted in the Page Down key being identified as "Next"
instead of "Page_Down"

"Page_Up" wasn't affected, since it comes before "Prior"

Signed-off-by: Olivier Brunel <jjk@jjacky.com>

https://bugzilla.gnome.org/show_bug.cgi?id=710411
Respect deprecated menu images setting

I have been convinced that it is a bad idea to change the behaviour
at the same time as deprecating it, so go back to respecting the
Gtk/MenuImages xsetting in GtkImageMenuItem when it is set.

The setting as well as the widget are still deprecated, and the
default value of the setting will remain FALSE.
Respect deprecated button images setting

I have been convinced that it is a bad idea to change the behaviour
at the same time as deprecating it, so go back to respecting the
Gtk/ButtonImages xsetting in buttons created with
gtk_button_new_from_stock() when it is set.

The setting as well as the function are still deprecated, and the
default value of the setting will remain FALSE.
Update expected results for some a11y tests

These are affected by recent changes to stock icons (adding
accessible names) and spinner sizing.