Change the configuration for the generated apidoc stubs.

Some of the changes, as a summary:

- Collapse the hierarchy to omit the QEMU namespace page
- Add more meaningful titles to the subpackages
- Prefer source ordering in most places
- Do not index pages that do not define their own symbols (via __all__)
- Show hidden members for qemu.aqmp.protocol, since this interface is
  designed to be extended.

Signed-off-by: John Snow <jsnow@redhat.com>