Rather than depending on some sleep value, start up an interpreter
as a subprocess and communicate with it. Because subprocess pipes
can't be read from until EOF and I want to read from them before that,
use ctypes to peek by using PeekNamedPipe. Once the subprocess has
written the message, then it is ready to roll and accept signals.
After that, kill it.

#5250: document __instancecheck__ and __subclasscheck__.  I hope the part about the class/metaclass distinction is understandable.

David Bolen's buildbot isn't know for it's speed, and it seems that we
may have been trying to kill the subprocess before it was fully
initialized. I ran with this change on the bot itself and it seemed to work.

(also an occasional source of bugs on the hgsvn-generated hg mirrors)

These failures occur on a Windows Server 2003 machine I test on.

 - note early on that the result of struct.pack includes padding
   bytes by default

 - add examples showing how order of struct fields can affect size
   (due to padding)

 - better headers and references; introduction to format strings

 - integrate packing notes into table

Many thanks to Meador Inge for the patch.

Instead of spaces between the filename and date (or whatever the string
is that follows the filename, if any) use tabs.  This is what the unix
'diff' command does, for example, and difflib was intended to follow
the 'standard' way of doing diffs.  This improves compatibility with
patch tools.  The docs and examples are also changed to recommended that
the date format used be the ISO 8601 format, which is what modern diff
tools emit by default.

Patch by Anatoly Techtonik.

Fixed a typo in the email.encoders module so that messages output using
an ISO-2022 character set will use a content-transfer-encoding of
7bit consistently.  Previously if the input data had any eight bit
characters the output data would get marked as 8bit even though it
was actually 7bit.

When such extra options include "-x testname", subsequent arguments
are all taken as test names to ignore. Therefore, standard options
must be passed before *TESTOPTS.

(witnessed on the ARM buildbots)

to cover recent locale changes and additions.