Remove index on tags(id) as id is already a primary key (so indexed).

This is redundant and isn't needed.
blending: add blend modes "HSV lightness" and "HSV color"

these two modes are only offered for modules acting in the RGB
color space; the underlying RGB <-> HSV conversions do not need to
clamp their inputs, thus allowing unbound values to be passed through;
should help to fix issue #9583.
be sure we can fully edit forms with the manager
highlights: sync opencl/c code paths.