-Wsign-compare warnings in unicodeobject.c.  These were all a result
of sizeof() being unsigned and being compared to a Py_ssize_t.
Not actual problems.

From Robert Collins.

cleanup overflowing handling in unicode_decode_call_errorhandler and unicode_encode_ucs1 (closes #22518)

limited by 100.

Patch by Claudiu Popa.

I accidentally merged this in 90b07d422bd9; this merge addresses the
last review comments on the patch.

I accidentally committed this in 6375bf34fff6; this changeset addresses the
last review comments on the patch.

This is a perennial question and something someone opens a ticket for probably
every other month or so, so I'm surprised we didn't already have a FAQ entry
for it.

The original patch was written by M. Votz, refined first by Ezio Melotti and
further refined by me.

This patch brings the pure-python datetime more in-line with the C
module.  Patch contributed by Brian Kearns, a PyPy developer.  PyPy
project has been running these modifications in PyPy2 stdlib.

This commit includes:

- General PEP8/cleanups;
- Better testing of argument types passed to constructors;
- Removal of duplicate operations;
- Optimization of timedelta creation;
- Caching the result of __hash__ like the C accelerator;
- Enhancements/bug fixes in tests.

Patch by Yongzhi Pan.

Pointed out by Arfrever.

Pointed out by Arfrever.

Corresponding functions now accept `const char *` (issue #1772673).

Patch by Ian Cordasco, approved by Éric Araujo.

Patch by Jonathan Hosmer.