Add canonical header link on each page to corresponding major version of the documentation.

Patch by Matthias Bussonnier.

using PySlice_GetIndicesEx() in debug builds.

variables.

buffer object with custom index object.

Some of the details of comparing mixed types were incorrect or ambiguous.
Added default behaviour and consistency suggestions for user-defined classes.
Based on patch from Andy Maier.

Patch contributed by Mariatta Wijaya.

exited to a stopped instead of terminated state (ex: when under ptrace).

Patch by Serhiy Storchaka.

* Mark up ``--help`` to avoid generating an en dash
* Use forward slash in Unix command line with a dollar sign ($) prompt

ctypes.CDLL instances.

Thanks Greg Bengeult for the patch.

Original patch by Chi Hsuan Yen.

Issue #29188: Support glibc 2.24 on Linux: don't use getentropy() function but
read from /dev/urandom to get random bytes, for example in os.urandom().  On
Linux, getentropy() is implemented which getrandom() is blocking mode, whereas
os.urandom() should not block.

In urllib, suffixes in no_proxy environment variable with
leading dots could match related hostnames again (e.g. .b.c matches a.b.c).
Patch by Milan Oberkirch.

Patch by jan matejek and Xiang Zhang.