Ristretto ported to cairo - bug-hunting

[Stephan Arts]

Hi,

The graphics functionality of ristretto have been ported to cairo.
This means that everything it used to do to determine how to render an
image has been overhauled.

In theory this means that everything might be broken now.

I've tested it using JPEG and PNG images, and so far I couldn't find
any regressions since 0.2.0

However, experience shows others are far better at pointing out my
mistakes then I am.

I want to ask you to test ristretto master, and report any bugs you
may find. (regressions or otherwise)

Kind regards,

Stephan Arts