python: Do not depend on access to internal data structures.
* lang/python/gpgme.i (gpgme_data_t): Rework so that it works without access to the definition of 'struct gpgme_data'. * lang/python/helpers.c (object_to_gpgme_data_t): Add assertion.
- Signed-off-by: Justus Winter <justus@g10code.com>