Fix #143.

Explanation: The JPEG format in plMipmap does not have to be an actual
JPEG image, it can also hold an RLE bitmap. libHSPlasma currently does
not attempt to compress any images held as uncompressed data and marked
JPEG, rather, it exports them as RLE maps. Maybe a bit odd, but it
works. I guess.

korman/properties/modifiers/render.py

@@ -248,7 +248,8 @@ class PlasmaLightMapGen(idprops.IDPropMixin, PlasmaModifierProperties, PlasmaMod
 
             # Mmm... cheating
             mat_mgr.export_prepared_image(owner=layer, image=lightmap_im,
-                                          allowed_formats={"PNG", "DDS"},
+                                          allowed_formats={"PNG", "JPG"},
+                                          extension="hsm",
                                           ephemeral=True,
                                           indent=2)