Delete excess glBein at GLwindowSolarMap::draw()
Expose orbitRadius parameter of OrbitCS to Squirrel

The internal name of the parameter is orbit_rad, but the name for
scripts is more consistent to naming conventions throughout the project.
Add ignorecs parameter to FindBrightestAstrobj

We occasinally want to ignore an Astrobj when searching for brightest
ones.  Namely, we ignore the Astrobj when we want to know lighting
environment around it.

Now TexSpheres do not take itself into account as a light source
when drawing spheres or spheroids.
Earth's shader accept multiple light sources like Moon

It was tough to rewrite the shader to adapt to multiple lights because
the Earth's shader is complex, but now it seems like working, judged
from moonlight reflecting on Earth.

The surface map is temporarily disabled to demonstrate new shader
for Earth.