Option to show NightTexture for eclipsed bodies

[LukeCEL]

Is your feature request related to a problem? Please describe. For some objects like Io, when it is eclipsed (such as behind Jupiter), only one side uses the NightTexture while the other side is completely black.

Describe the solution you'd like There could be an option, like a boolean parameter. When set to true, the eclipsed surface would show the night texture

Additional context The reason this should be a boolean and not the default texture is because sometimes you don't want the NightTexture to show (e.g. when Earth experiences a solar eclipse - the night lights don't turn on).

This is a relatively low-priority request.

[LukeCEL]

Here is a picture of Io, behind Jupiter. I've marked the terminator (the yellow line) to show the two hemispheres.

[375gnu]

In 1.7 we have night texture in an eclipse zone: