cleanups in Material, use instance creation util function
cleanups in Material, use instance creation util function

MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,wilsonCernWq/ospray,MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray,wilsonCernWq/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay,ospray/OSPRay