Sky: Draw bottom of the sky box in 'cloudy fog color'

To be identical to the lower half of the skybox sides.
Now needed as the skybox base is often seen due to increasingly vertical
mapgens.

src/sky.cpp

@@ -232,6 +232,14 @@ void Sky::render()
 			driver->drawIndexedTriangleFan(&vertices[0], 4, indices, 2);
 		}
 
+		// Draw bottom far cloudy fog thing
+		video::SColor c = cloudyfogcolor;
+		vertices[0] = video::S3DVertex(-1, -1.0, -1, 0, 1, 0, c, t, t);
+		vertices[1] = video::S3DVertex( 1, -1.0, -1, 0, 1, 0, c, o, t);
+		vertices[2] = video::S3DVertex( 1, -1.0, 1, 0, 1, 0, c, o, o);
+		vertices[3] = video::S3DVertex(-1, -1.0, 1, 0, 1, 0, c, t, o);
+		driver->drawIndexedTriangleFan(&vertices[0], 4, indices, 2);
+
 		driver->setMaterial(m_materials[2]);
 
 		// Draw sunrise/sunset horizon glow texture (textures/base/pack/sunrisebg.png)