This release adds support for linear and radial gradients. The paint
hierarchy has also been restructured and as a result a new wrapper for
cairo contexts has been implemented that includes internal state
values. The Paint class is now a top level ancestor for all paints,
including the gradients. The former solid colors that were supplied
by Paint can now be found in its descendant Color.

Other changes include a fix in ScrolledViewport for a display bug and
the restructuring of several primitives such as Point, Vertex and
LineSegment.