Updated all display class clone methods.

Signed-off-by: Grant Skinner <info@gskinner.com>
Improved AlphaMapFilter.clone()

Signed-off-by: Grant Skinner <info@gskinner.com>
Added geom methods to Rectangle.

extend, intersection, union, intersects, contains, isEmpty

Signed-off-by: Grant Skinner <info@gskinner.com>