Revert "dialog: Fix docs for GtkDialog"

This reverts commit e4bb02f8ae698facc204c616108cc8f4c3b579bc.

Responses don't have to be negative.
Updates
GtkWidget: Fix clipping to large subwindows

_gtk_widget_draw_internal() was clipping by passing the subwindow
sizes as a path to cairo_clip(). This was breaking for windows
larger than 23 bits in width/height, due to cairo using fixed point
(24.8) for the path coordinates.

We fix this by pre-clipping the subwindow region to the existing
cairo clip region in the full 32bit gdkwindow precision. This fixes
the GooCanvas Large Items test.

https://bugzilla.gnome.org/show_bug.cgi?id=710958
Remove debug spew
Update the release notes
Fix up accessibility tests

The output had gotten debug spew in it.
Bump version
gtkdialog: Allow specifying response IDs by nick in <action-widgets>

This makes it a lot more convenient for developers, as they don't
have to look up the numeric value of response IDs.