This routine adds the Geometry Definition object to the Library. (If the Geometry Definition passed in is
None, this Geometry Definition will not be added to the Library.) There is no checking for duplicates when adding a Geometry Definition. This call will always add the Geometry Definition to the Library, even if an identical one already exists therein. If there are any errors in operation an exception is raised. If the addition is successful, a unique geometry definition reference ‘key’ that is associated with the Geometry Definition is returned.