*fix: area_illumination syntax updated to fix bug in area lights
*fix:sphere sweep was buggy (bezier curve would'nt export)
*several curves in one blender object can now export Thanks Lanuhum
*fix:hair with no material slot would'nt export
*fixemodifier like subsurf or mirror over curves wouldn't export, now trying to convert to mesh
*fix:meshes with 0 vertices wrote a bad file,  now create a dummy 0 radius sphere
*fix: export visible layer only was broken