* Default to white when setting LIFX temperature
Changing the temperature of a saturated color is possible but not very
interesting. So assume that a change of the temperature implies setting
the color to white, unless a different color is actually specified.
This makes the frontend temperature picker much more useful because it can
now be used to get away from a colored light.
* Default to a neutral white temperature when setting LIFX colors
This means that setting a particular color will always give the same output,
no matter what the temperature was previously at.
* Find brightness after colors
Now the color_temp logic will not see a changed color when setting
temperature+brightness and thus we will actually get a white light in
this situation.
The XY conversion can then not use brightness as input. This is not
an issue because XY only affects hue and saturation, not brightness. So
we can just use an arbitrary value as brightness input.
* Add a simple comment to a complex conditional
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