Fixed|Map Renderer: Plane glow disappears when plane is moving

The glow's origin Z coordinate was not smoothed and thus below the
visible height of the plane, making the glow disappear while the plane
was moving upward. (Hexen MAP04 opening room)

doomsday/engine/portable/src/r_lumobjs.c

@@ -995,6 +995,7 @@ static boolean createGlowLightForSurface(Surface* suf, void* paramaters)
         // @note Plane lights do not spread so simply link to all BspLeafs of this sector.
         lum = createLuminous(LT_PLANE, sec->bspLeafs[0]);
         V3d_Copy(lum->origin, pln->PS_base.origin);
+        lum->origin[VZ] = pln->visHeight; // base.origin[VZ] is not smoothed
 
         V3f_Copy(LUM_PLANE(lum)->normal, pln->PS_normal);
         V3f_Copy(LUM_PLANE(lum)->color, avgColorAmplified->color.rgb);