Fixed a bug in the spin deletion unit test 'test_delete_num'.
Fixed a bug in the spin deletion unit test 'test_delete_shift'.
Fixed a bug in the spin deletion unit test 'test_delete_all'.
Fixed the spin creation 'test_creation' unit test.
Removed the RelaxError when spin selections are feed into the residue loop.
Implemented the generic_fns.spin.delete() function.
Added 4 unit tests for the generic_fns.spin.delete() function.
Debugged the spin creation function.
Fixed another bug in the spin creation unit test.
Implemented the generic_fns.spin.create() function.