Astronomy overlay layers

[kylecorry31]

The following could be overlay layers that display over the top of the map (so not normal layers).

Would need to add an option to let users hide/show them (current layer management does not support overlay layers).

I'm not sure if I will implement all of these (ex. the sky map versions)

Sun

• Display the sun as an overlay, like the radar compass (using map center)
• Option to hide when below horizon
• Option to display on "sky map" compass (elevation = distance from center)

Moon

• Display the moon as an overlay, like the radar compass (using map center)
• Option to hide when below horizon
• Option to display on "sky map" compass (elevation = distance from center)

Stars (and constellations)

• Option to display on "sky map" compass (elevation = distance from center)