Gphoto2

1/ Reinstated Context.camera_autodetect method removed in 2.2.0.

1/ COMPATIBILITY CHANGE: Removed Context.camera_autodetect method.
2/ COMPATIBILITY CHANGE: Removed deprecated widget get/set functions.
3/ Python3 log messages are now str instead of bytes.
4/ Documentation improvements.

1/ COMPATIBILITY CHANGE: gp_file_set_data_and_size and gp_file_append now
take a single buffer parameter (such as a bytes string) instead of a
string and length.
2/ Fixed memory double free bug in gp_file_set_data_and_size.
3/ Removed support for libgphoto2 v2.4.

1/ COMPATIBILITY CHANGE: gp_log_add_func and use_python_logging now return a
Python object which must be stored until logging is no longer needed.
2/ Added cam-conf-view-gui & wait-for-event examples. Thanks to the users who
contributed these.
3/ Various minor bug fixes and improvements.

1/ Enabled use of context callback functions such as
gp_context_set_progress_funcs.
2/ Added a time lapse movie example script.

1/ Fix memory leak in gp_camera_get_config.