Highlights:

* New ways to set up client connections:
  - For cloud-based services, it should suffice to pass username, password and the name of the service, no URL needed (though, just some few providers supported so far)
  - If the username is in email format, then it's generally not needed to pass a URL.
* v2.2 comes with lots of workarounds around lack of feature support in the servers - notably the sync-token API will work also towards servers not supporting sync-tokens.  In some cases lack of server functionality is detected, but as for now it may be needed to specify what server one is user through the `features` configuration flag.
* v2.2 supports more complex searches.  Client-side filtering will be utilized for the things that aren't supported on the server side.

v2.2.0 comes with the requests dependency, v2.2.1 comes with niquests dependency