This release is compatible with version 2.0.0.
* Don't print warning when cache format changes
* Add documentation for `BaseAuth`
* Add `is_authenticated2(login, user, password)` to `BaseAuth`
* Fix names of custom properties in PROPFIND requests with
`D:propname` or `D:allprop`
* Return all properties in PROPFIND requests with `D:propname` or
`D:allprop`
* Allow `D:displayname` property on all collections
* Answer with `D:unauthenticated` for `D:current-user-principal` property
when not logged in
* Remove non-existing `ICAL:calendar-color` and `C:calendar-timezone`
properties from PROPFIND requests with `D:propname` or `D:allprop`
* Add `D:owner` property to calendar and address book objects
* Remove `D:getetag` and `D:getlastmodified` properties from regular
collections