Linked material type to read Corona mtl

[Eneen]

Like VRayVRmatMtl in Vray or referenced MXM in Maxwell. That would be nifty feature to share materials between projects, to keep nice organized lib and to share materials between e.g. max and blender

[Ondra]

Essentially a duplicate: https://forum.corona-renderer.com/index.php/topic,7913.0.html