Updated Prefer Header Draft

The last call on the Prefer draft has closed as of today. Based on the
excellent feedback I received during the last call, I have updated the
current draft and it has been handed off for IESG review. The current draft
is located here

 http://www.ietf.org/id/draft-snell-http-prefer-15.txt

The major changes based on feedback include:

1. I have brought back the Preference-Applied response header. I know that
there are a few folks who feel this header is entirely unnecessary but
feedback I have received from a number of implementers has convinced me it
is. The use is optional and limited to cases where the application of a
preference may not be obvious and the application of the preference could
have an impact on the processing of a response.

2. I have altered the definition of the wait preference slightly.
Essentially, it now specifies the clients assumption of how long processing
a request should take rather than indicating how long the client is willing
to wait for a response. The difference is subtle but important, and the
change is a very good one.

3. I have made a number of editorial changes to the structure of the
document. Some section numbers have changed.

- James