---------------------------------
**Changes**
- Rename ``door.utilities.Resource`` to ``door.utilities.Proxy``.
- Separate and move ``door.utilities.Door`` into ``door.doors.AcquirableDoor``
and ``door.doors.SAcquirableDoor``.
- Separate and move ``door.utilities.AsyncDoor`` into
``door.doors.AsyncAcquirableDoor`` and ``door.doors.AsyncSAcquirableDoor``.
- Remove ``door.primitives.AsyncPrimitive`` and
``door.primitives.FineGrainedAsyncPrimitive``.
- Fix documentations.
**Additions**
- Add ``door.primitives.Waitable``, ``door.doors.WaitableDoor``,
``door.doors.AsyncWaitableDoor`` for conditional variables.
- Add ``door.utilities.await_if_available``.