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.

v2.2.1 comes with request dependency, v2.2.2 comes with niquests dependency (and v2.2.0 comes with misspelled riquests dependency)