- Return a tuple of newlines in stead of 'mixed'
- Added rationale for having the code in ifdefs and not having the
newlines attribute in --without-universal-newlines builds.
- U is the mode character that signal universal newlines in open in stead
of t.
- Clarified why output isn't handled.
- Clarified various questions on unicode, exec, locks, etc.
Andrew M. Kuchling
Jack Jansen
Guido van Rossum
Barry Warsaw