Blender Git Loki

Node shader wrapper: use 'Non-Color' profile for BW textures inputs.

All the single-value texture inputs of Principled BSDF node should use
non-color colorspace profile, not sRGB one (issue raised in
https://blender.stackexchange.com/questions/155617, thanks).

That also revealed another issue - since those color space settings are
stored at the image level itself, not the node one, we need to
duplicate those image data-blocks when we use same picture for e.g. base
color (sRGB) and specular (non-color) inputs...

For now using a basic mechanism for that, might generate several extra,
uneeded copies of the image ID, but that?s better than breaking custom
settings and such.

Note that while this will modify the behavior of the impporters using
that node wrapper, no change should be needed in IO add-ons themselves.