* Access rights are checked before the storage is locked and
collections are loaded.
* DELETE sends 410 instead of doing nothing or crashing if the target
doesn't exist.
* GET always returns 404 if the target doesn't exist.
* GET doesn't crash if a collection without tag property is requested.
* MKCOL and MKCALENDAR send 409 if the target already exists.
* MOVE checks if the target collection of an item actually exists and
sends 409 otherwise.
* PUT doesn't crash if a whole collection that doesn't exist yet is
uploaded and ``content-type`` is ``text/vcard`` or
``text/calendar``.
* PUT distinguishes between simple items and whole collections by the
following criteria: Target is a collection; Parent exists; Parent
has the tag property set; Parent contains other items. Before only
the first two criteria where used, which was very unrelieable. #384
* PROPPATCH is only allowed on collections and 409 is send otherwise.
* ``Rights.authorized`` takes a path instead of a collection.
* ``Collection.discover`` only returns items in ``path``, that
actually exist. #442
When the request path leads to a non-existing item, try to create the
Collection object according to an existing collection at request path's
parent.
This change means that the requests whose path leads to a collection
that doesn't exist (at least MKCOL, MKCALENDAR and PUT) need to rely on
the request path more than on the Collection path. It was already done
for PUT, it's been fixed for MKCOL and MKCALENDAR.
Fix#378.
The new API used comes from vdirsyncer, as proposed by @untitaker in
issue #130.
The code has been tested and works with the (too simple) unit tests, and
with Lightning and DAVdroid. Many things are broken and a good part of
the code has not be ported to the new API yet. TODOs have been added
where the application is known to be broken.
