This patch introduces a way to tweak the coordinate systems per
domain. The 'origin' attribute denotes the origin of the coordinate
system. Valid values are "top_left", "top_right", "bottom_left",
"bottom_right", and "pointer". Furthermore, the screen dimensions as
reported to the nitpicker client can be tweaked per domain using the
'width' and 'height' attributes. If the specified value is positive,
it is taken as literal boundary. If the value is negative, the size
if deducted by the specified amount from the physical screen area.
This patch introduces a mandatory layer attribute to domains. The layer
ordering is superimposed on the stacking order of the views. The
top-most layer can be assigned to a pointer-managing client. An example
for such a pointer is located at os/src/app/pointer. It replaces the
formerly built-in nitpicker mouse cursor.
The new layering mechanism replaces the former "stay-top" session
argument. So the Nitpicker::Connection no longer takes the stay-top flag
as the first argument.
