#8292: Fix three instances of truth tests on return values of filter() (which is always true in Python 3).

at import time, rather by default use the current streams like the
other APIs that output help.

#7909: the prefixes \\.\ and \\?\ indicate special Windows paths, do not try to manipulate them.  See http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx for details.

#3788: more tests for http.cookies, now at 95% coverage.  Also bring coding style in the module up to PEP 8, where it does not break backwards compatibility.

#9442: do not document a specific format for sys.version; rather refer to version_info and the platform module.

#9440: Remove borderline test case that fails based on unpredictable conditions such as compiler flags.

I removed the implicit conversion from str to bytes.

Copy Sun-specific inclusion of <alloca.h> from 2.7 maint to trunk; it seems to not have been merged to py3k.