Function: url-dav-request

Perform WebDAV operation METHOD on URL. Return the parsed responses.
Automatically creates an XML request body if TAG is non-nil.
BODY is the XML document fragment to be enclosed by .

DEPTH is how deep the request should propagate. Default is 0, meaning
it should apply only to URL. A negative number means to use
`Infinity' for the depth. Not all WebDAV servers support this depth
though.

HEADERS is an assoc list of extra headers to send in the request.

NAMESPACES is an assoc list of (NAMESPACE . EXPANSION), and these are
added to the element. The DAV=DAV: namespace is automatically
added to this list, so most requests can just pass in nil.

(fn URL METHOD TAG BODY &optional DEPTH HEADERS NAMESPACES)