[sldev] s/maint-render/render-pipeline/g

[Brad Kittenbrink (Brad Linden)]

There's been a bit of discussion internally lately, and we came to the 
conclusion that maint-render has had a lot going on in it that doesn't 
count as simply maintenance (for example when shadow-draft merged into it).

To reflect that the ongoing work on the renderer is generally in the 
form of larger scale projects, we've renamed the maint-render branch 
series to be render-pipeline.  So, render-pipeline-1 (I believe 
exporting as I write this) is what would have been maint-render-12.

In summary, if you've been tracking the maint-render branches, they're 
now called render-pipeline, so have at it...

cheers,
-Brad