[cairo] Testing Performance SVGSurface/PDFSurface as meta surfaces

[Stuart Axon]

I thought I'd test my app with SVGSurfaces vs PDFSurfaces as meta surface standins.

SVGSurface is seems much quicker:

Draw 1000 frames:
SVGSurface:  1m28
PDFSurface:  1m48

Running a few times, the wallclock time is the same to within a couple of seconds.
It might be down to the nature of my app (shoebot running a bot that 
animates a lot of circles)

Note:  I'm aiming for 60fps, so quite a long way to go.



Another quick note:  In windows SVGSurface(None, w, h)  says it's missing a file object, so I have to pass in 'nul'
 S++