make build install
A .desktop file is included. With it installed to your ~/.local/share/applications directory, you get a Unity launcher item.
A c source file is included (rather than using a script) so that it can be given to the root user and have its user bit set.
Run the desktop file, and you get a panel of buttons for altering redshift (gamma) and bright (backlight). You need to supply images for the buttons yourself (not included for copyright reasons). See the IMG_* variables at the top of the python script.
bright # read the current bright value
bright + # double the current bright value
bright - # halve the current bright value
bright +X # increment the current bright value by X
bright -X # decrement the current bright value by X