Module coords.pytpm_wrapper

This routine wraps the pytpm.blackbox routine in order to apply
the longitude convention preferred in coords. All astrolib.coords routines
should call pytpm_wrapper.blackbox() instead of pytpm.blackbox().
    Since pytpm is itself a wrapper for the TPM library, the change could
have been made there; but the modulo operator in C only works on integers,
so it was simpler to do it in python. Also, this leaves pytpm itself as a more
transparent wrapper for TPM.