Add osgScaleViewer

[eile]

Code: https://github.com/Eyescale/Equalizer/tree/master/examples/osgScaleViewer

Overview: http://www.equalizergraphics.com/applications/osgScaleViewer.html

[xarray]

Thanks for the idea.

I have read the osgScaleViewer before but was unsatisfied to its implementation, which uses Equalizer as the actual renderer and copies too much code from the OSG which makes the whole example fat. I'd like to consider merging Equalizer into OSG viewer instead and will put the plan into my TODO list. :-)

[eile]

I agree that the copied code is suboptimal. However at the time there where issues with the way stereo rendering is handled in the osg SceneView and osgViewer which made it impossible to render a single eye only (or one anaglyph mask), iirc.

Moving the necessary changes to osg would be a good move indeed.

[xarray]

Thanks eile. I'd like to think about designing such a recipe in future. You and others are also welcomed to contribute. :-)