Merge branch 'rav/more_group_chat/1'

include/olm/error.h

include/olm/inbound_group_session.h

include/olm/megolm.h

include/olm/message.h

include/olm/message.hh

include/olm/olm.h

include/olm/outbound_group_session.h

include/olm/pickle_encoding.h

python/.gitignore

python/olm/__init__.py

python/olm/__main__.py

python/olm/inbound_group_session.py

python/olm/outbound_group_session.py

python/test_olm.sh

src/error.c

src/inbound_group_session.c

src/megolm.c

src/message.cpp

src/olm.cpp

src/outbound_group_session.c