honor the MacOSX SDK when one is specified.

This is needed to be able to build using the 10.4u SDK while running
on OSX 10.6.

This is a fixed version of the patch in r80963, I've tested this patch
on OSX and Linux.

Fixes (mysterious, to the end user) UnicodeErrors when using utf-8 as
the charset and unicode as the _text argument.  Also makes the way in
which unicode gets encoded to quoted printable for other charsets more
sane (it only worked by accident previously).  The _payload now is encoded
to the charset.output_charset if it is unicode.

default of unbuffered IO in subprocess.Popen.

False on MacOSX 10.5 or earlier and scripts won't be able to access GUI
functionality.

configured before attempting to test PlaySound.

Put docs for RegexObject.search() before RegexObject.match() to mirror re.search() and re.match() order.

and a complex instance.  Based on a patch by Meador Inge.

type.  Coercion for arithmetic operations was already removed in
r78280, but that commit didn't remove coercion for rich comparisons.

pipe communication into a loop to retry in case a buildbot gets even slower.

gaierror(EAI_NODATA)

timedelta from date or datetime falls outside of the MINYEAR:MAXYEAR range.

using unittest.skipIf decorator.

including Windows CE.

error handler, instead of writing to the C stderr file in utf-8

ports of IronPython tests.  Thanks Gregory Nofi.

unquote is duplicated in the two files to avoid a circular reference.
(This is fixed in Python3.)  Updates keep getting made to the public unquote
without fixing the urlparse one, however, so this fix syncs the two
and adds a comment to both to make sure changes are applied to both.