Issue 2235: __hash__ is once again inherited by default, but inheritance can be blocked explicitly so that collections.Hashable remains meaningful

Works on issue #2877. Thanks Quentin Gallet-Gilles for the patch.

 - Specialcase extended slices that amount to a shallow copy the same way as
   is done for simple slices, in the tuple, string and unicode case.

 - Specialcase step-1 extended slices to optimize the common case for all
   involved types.

 - For lists, allow extended slice assignment of differing lengths as long
   as the step is 1. (Previously, 'l[:2:1] = []' failed even though
   'l[:2] = []' and 'l[:2:None] = []' do not.)

 - Implement extended slicing for buffer, array, structseq, mmap and
   UserString.UserString.

 - Implement slice-object support (but not non-step-1 slice assignment) for
   UserString.MutableString.

 - Add tests for all new functionality.

and UserString.MutableString.__delitem__.

tracebacks. (Suggested by Walter Dörwald)

addition to unicode objects.

(Spotted by Raymond Hettinger)

 * Doc - add doc for when functions were added
 * UserString
 * string object methods
 * string module functions
'chars' is used for the last parameter everywhere.

These changes will be backported, since part of the changes
have already been made, but they were inconsistent.

Closes SF Bug #592573 where inplace add mutated a UserString.
Added unittests to verify the bug is cleared.

imports of test modules now import from the test package.  Other
related oddities are also fixed (like DeprecationWarning filters that
weren't specifying the full import part, etc.).  Also did a general
code cleanup to remove all "from test.test_support import *"'s.  Other
from...import *'s weren't changed.

I'm getting better at vi!

Add a method zfill to str, unicode and UserString and change
Lib/string.py accordingly.

This activates the zfill version in unicodeobject.c that was
commented out and implements the same in stringobject.c. It also
adds the test for unicode support in Lib/string.py back in and
uses repr() instead() of str() (as it was before Lib/string.py 1.62)

Add optional arg to string methods strip(), lstrip(), rstrip().
The optional arg specifies characters to delete.

Also for UserString.

Still to do:

- Misc/NEWS
- LaTeX docs (I did the docstrings though)
- Unicode methods, and Unicode support in the string methods.

and introduces a new method .decode().

The major change is that strg.encode() will no longer try to convert
Unicode returns from the codec into a string, but instead pass along
the Unicode object as-is. The same is now true for all other codec
return types. The underlying C APIs were changed accordingly.

Note that even though this does have the potential of breaking
existing code, the chances are low since conversion from Unicode
previously took place using the default encoding which is normally
set to ASCII rendering this auto-conversion mechanism useless for
most Unicode encodings.

The good news is that you can now use .encode() and .decode() with
much greater ease and that the door was opened for better accessibility
of the builtin codecs.

As demonstration of the new feature, the patch includes a few new
codecs which allow string to string encoding and decoding (rot13,
hex, zip, uu, base64).

Written by Marc-Andre Lemburg. Copyright assigned to the PSF.

added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.

rfc822 (Addresslist) modules. Also a preliminary testcase for augmented
assignment, which should actually be merged with the test_class testcase I
added last week.

Let UserString.translate() method work with unicode data.

This closes SourceForge patch #101246.

The maxsplit functionality in .splitlines() was replaced by the keepends
functionality which allows keeping the line end markers together
with the string.