proper CAN headers.

This applies only to the new parser.  The old parser decodes encoded words
inside quoted strings already, although it gets the whitespace wrong
when it does so.

This version of the patch only handles the most common case (a single encoded
word surrounded by quotes), but I haven't seen any other variations of this in
the wild yet, so its good enough for now.

This is a bit of an ugly hack because of the way generator pieces together the
output message.  The deepcopys aren't too expensive, though, because we know it
is only called on messages that are not multiparts, and the payload (the thing
that could be large) is an immutable object.

Test and preliminary work on patch by Vajrasky Kok.

Patch mostly by Serhiy Storchaka.

input was truncated in BASE64 section.

This fixes a regression relative to python2.

I'm checking this in without a test because not much of this code
is tested and I don't have time to work up the necessary extensions
to the existing test framework.

The patch itself was tested by the person who reported the bug.

Patch by Berker Peksag.

import and not *an* implementation.

containing non-encodable characters.  Added tests for TarFile.list().
Based on patch by Vajrasky Kok.

CID 1167595

The '**' operator is available only since 8.5 and in any case such large
integers are not supported on Tcl <8.5.

Issue #20426: When passing the re.DEBUG flag, re.compile() displays the debug output every time it is called, regardless of the compilation cache.

Improved error handling in variables-related commands.

exprlong() and exprboolean().