Translating newlines to fix embedded carriage returns

A frequent, and especially troublesome to debug, cause for post-review issues
is embedded carriage returns. These are fine if they occure as a windows
newline, but when a \r isn't followed by a \n the patch command run on the
ReviewBoard host will usually choke due to misaligning line numbers in the
following chunks. Tested by running...

% p4 edit README
% echo "more\rstuff\r\n" >> README
% post-review

This produced a server-side stacktrace without this patch, and works with this
normalization.