Blender Git Loki

Feature + Fix:

- while sampling color in image window, you now get the sampled color as a line
drawn in the node editor Curve nodes, allowing quicker view of what values you
actually change.

- reverted temporary the patch [#6779] by Matthew Plough
He replaced image drawing of backdrop-node-editor with our Texture drawing
function. That call is extremely slow, and should be by definition slower
than glDrawPixels (unless you don't upload the image each time to gfx mem).

Drawing large frames (2k, 4k) in node editor became unacceptable slow, even
with the neatest hardware around. (tested nvidia, ati)

Probably (Campbell thinks) this is a bypass for Linux ATI cards?
Anyhoo, this should be investigated further before applying. It better then
becomes a user pref, or even much better: part of the OpenGL profiler we need.