WRITE_DAV_PROP: Summary of consensus

Let me see if I can summarize the points of consensus on this issue:

Consensus:

- protected (i.e. properties that MUST NOT be modifiable with PROPPATCH)
  creationdate
  getcontentlength
  getetag
  lockdiscovery
  supportedlock
  resourcetype

- not protected (i.e. properties that MUST be modifiable by PROPPATCH)
  displayname
  source

Still under discussion:

  getlastmodified
  getcontenttype
  getcontentlanguage

There are two open issues:

1. Changing get* properties requires the server to perform a property lookup
when processing a GET method request, and this is a performance hit for some
servers.

2. It is unclear why getlastmodified needs to be writeable.

Let's see if we can resolve these remaining issues over the next 1-2 days,
so we can wrap this one up.

- Jim