PsppireOutputWindow: Draw the entire page instead of just the exposed area.

PsppireOutputWindow: Draw the entire page instead of just the exposed area.

Gtk3 doesn't require (or provide the necessary information for) the drawn
widget to be cliped to the exposed area.  So this change removes the clip
from the expose callback of the PsppireOutputWindow.  It also removes some
functions which are now not necessary.