g-s-d was changed to use a better black body temperature calculation.
This strongly affects the effect of the color temperature (the default
is changed from 4000K to 2700K). Update the scale to represent a similar
range to default even if the distribution on the scale is quite
different.
It's good to have some space between the to and from widgets, so
they aren't squashed, and so they blend better with the colour
temperature slider below.
Ideally we'd just increase the space between the to and from
sections, and not also between the widgets and their labels, but
the approach in this commit isn't too bad.
The new Night Light page, as described by the latest mockups [1],
uses a listbox to display the options. Also, there is a small
revamp on how the disabled state is handled; it now is a switch
in a row, instead of an extra radio button.
This commit changes the Night Light page to have a listbox, and
uses libhandy's rows to achieve the desired interface.
Fixes https://gitlab.gnome.org/GNOME/gnome-control-center/issues/533
