Blender Git Loki

Last new feature before release; patch provided by Goran Kocov.

In DisplayButtons, Panel "Output", a new slider "Dither" allows to add
random noise dither to rendered output. It works on sky as well as solid
and transparent. Note however that in OSA render, the Unified Render gives
much better results, since that render nicely delivers full scanlines of
high definition color. The old render mode isn't well suited for this
postprocess.

A dither value of '1.0' will exactly add maximum of 1.0/256.0 to the
pixels.

Potential improvements for next releases;
- regular patterns
- dither per color channel
- not only add, but also subtract dither

Also note that this gives best results for print work or stills. Animating it
gives slight visible noise. Also runlength compression wont really work, and
Jpeg needs to be given higher quality too.