A lot of improvements. As it is difficult to separate each scope, the following list summarizes the most important changes:

 * Replaced all the yield from syntax to async/await syntax for asyncio calls
 * Moving from aionotify to watchdog. aionotify was not actively developed since 2 years. watchdog is actively developed. although is not directly asynchronously usable but hachiko can be used as a helper.
 * Added some options to enable or not the muc/pubsub features. If your XMPP account does not have a proper pubsub service or if you don't want to advertise your file transfer, these functionalities are not mandatory anymore.
 * Misc small improvements