Copy color3way plugin from HV 4.5.
Add new method BC_Slider::set_pointer_motion_range().

This method is used by the color3way plugin ported from
Cinelerra HV 4.5.
Backport color3way plugin.

Adjust plugin to use the CV plugin API, convert it to automake
and add the required images to the suv theme.

The code to save and load defaults are missing.