Only set runtime colors to black if we are not preshading.

Otherwise, what we wind up doing is making it pretty much impossible for
RT lights to affect objects with kLiteMaterial.

korman/exporter/material.py

@@ -1184,7 +1184,7 @@ class MaterialConverter:
         return utils.color(color)
 
     def get_material_runtime(self, bo, bm, color=None) -> hsColorRGBA:
-        if not bo.plasma_modifiers.lighting.rt_lights:
+        if not bo.plasma_modifiers.lighting.preshade:
             return hsColorRGBA.kBlack
         if color is None:
             color = bm.diffuse_color