add a gamma setting that is not an error correction

Signed-off-by: Mattias Andrée <maandree@operamail.com>
add lookup table adjustment

Signed-off-by: Mattias Andrée <maandree@operamail.com>
LUT adjustment both before and after gamma, brightness and temperature

Signed-off-by: Mattias Andrée <maandree@operamail.com>