Blender Git Loki

New Curves Widget option: curves can get extrapolated extension.
Especially for Compositing it was annoying that colors always got clipped
in the 0.0-1.0 range. For this reason, extrapolated Curves now is the
default. Old saved files still have horizontal extrapolation.

Set the option with 'Tools' menu (wrench icon). This is a setting per
curve, so you might need to set all 4 curves for an RGBA curves widget.