This was rather a TODO item related on supporting the proper painting color
space, but added a small tweaks which will make things working for now in
most of the situation (assuming the default view of display is ivnertible,
as it is to be expected to be anyway).
Shouldn't give much overhead since the conversion processors are cached in
the color management code.
And for the note: no, projection painting does not requite such a tweak
because viewport works in sRGB space anyway.
e6ff0ec73d