solution could have been much simpler, but since that would have required
altering blender code (only a single line though)...
also fixed a minor bug reported in the yafray forums, when spotlights had the
shadowbuf flag set and then switching to yafray, yafray still rendered
shadows which to user was unexpected since there was no shadow flag enabled
in the yafray lamp panel, so now ignores the blender flag.
193015653f