docs: python bindings howto
docs: python bindings howto

* Complete typographic overhaul.
* Removed all section level indentation since it does not affect
  output formatting, but might affect source code examples.
* In text-mode stripped out all tabs which had crept in and replaced
  them with four spaces.
* Updated all code examples (again) to conform with Python-mode.
* Bumped version number in preparation for next release of GPG 2.2.9
  and corresponding GPGME release.

gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme