[cairo] PyCairo, make a copy of a Matrix

[Stuart Axon]

> m4=cairo.Matrix(m1)

> Does not work. But it 
> might be useful to add it for consistency with the
> way that Python list, 
> dict, int work.
> 
> Steve
>
This would be good, it was one of my first ideas.
I'd imagine this may be more performant too.