Apply gamma after brightness and termperature

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Merge pull request #46 from maandree/gamma

Apply gamma after brightness and temperature
Fix #40: redshift-gtk: toggle_item is checkbox that follows the icon

Signed-off-by: Mattias Andrée <maandree@operamail.com>
[redshift-gtk] Add BSD support to proc title setting
Fix #22: remove initial underscore from include guards