Color Picker Hex and RGB Fields should use the Empty Color

[jordandh]

Describe the idea you have
When deleting the hex value in the hex field of the color picker set the color equal to the empty color instead of #000000.
This is less arbitrary and gives more control to the library user.

As an additional feature always show the hex and rgb fields even when the color is equal to the empty color. The fields can show the value of the empty color or be blank if the empty color is falsey. This gives the user the option of typing in the color value when there is no initial color selected.