[racket] CRLF vs LF & windows

I've pushed a change today in the way that DrRacket handles line
endings under windows. If you are a regular windows user who has the
energy to give the pre-release a try for your usual DrRacketeering for
a week or month or so to share you feedback on this change, that'd be
great.

In old versions, DrRacket would open a file in any style and then save
it using CRLF (under windows; it would always save regular LF files on
other platforms). In the current pre-release, DrRacket checks to see
if every line ends in CRLF in the file and, if so, it saves the file
in CRLF (and puts a little warning in the bottom of the window that it
is in this mode). Otherwise, it saves the file in LF mode. There is a
preference to go back to the old behavior too.

Feedback welcomed.

Thanks,
Robby