Fix a bug in lunar eclipse rendering

The function 'computeModelMatrix' was returning the wrong matrix,
because the transformations chain applied the local rotation before the
parent body translations.  This resulted in the Earth and Sun position
used in the shadow computation to be rotated from the center of the
Moon, making the shadow looks like it was seen from an observer outside
of Earth.

I commit this even though we should test a bit more, because a lunar
eclipse is coming.

src/core/modules/Planet.cpp

@@ -2449,13 +2449,14 @@ void sRing(Ring3DModel* model, const float rMin, const float rMax, int slices, c
 
 void Planet::computeModelMatrix(Mat4d &result) const
 {
-	result = Mat4d::translation(eclipticPos) * rotLocalToParent * Mat4d::zrotation(M_PI/180*(axisRotation + 90.));
+	result = Mat4d::translation(eclipticPos) * rotLocalToParent;
 	PlanetP p = parent;
 	while (p && p->parent)
 	{
 		result = Mat4d::translation(p->eclipticPos) * result * p->rotLocalToParent;
 		p = p->parent;
 	}
+	result = result * Mat4d::zrotation(M_PI/180*(axisRotation + 90.));
 }
 
 Planet::RenderData Planet::setCommonShaderUniforms(const StelPainter& painter, QOpenGLShaderProgram* shader, const PlanetShaderVars& shaderVars) const