fixed: also check new (v2.3.1) spelling of header dir (collada-dom) for system dirs      : check COLLADA_ROOT_DIR environment variable if the cmake variable of the        same name is not set
fixed: also check new (v2.3.1) spelling of header dir (collada-dom) for system dirs
     : check COLLADA_ROOT_DIR environment variable if the cmake variable of the
       same name is not set

jondo2010/OpenSG,jondo2010/OpenSG,jondo2010/OpenSG,jondo2010/OpenSG,jondo2010/OpenSG