I've added a working GLSL image viewer example.

It relies on OpenImageIO to load an arbitrary image, and then will
display it using OpenColorIO. It's pretty awesome to see how little
code in practice is needed to implement a full-fledged monitor
interface!
(Including fstop exposure controls, channel swizzling, etc).

For those interested in adding OCIO natively to existing viewers, this
is a great place to start

Commits:
18ac496924e06
899b272d710ea

Caveot : this doesn't yet work with the CMake makefile, I hope to get
that added soon.

-- Jeremy