[Distutils] Pip 10 is nearing release

[Paul Moore]

After much work, we're pleased to announce that pip 10 is finally
nearing release. We're planning on releasing a beta version over the
weekend of 31 Mar/1 Apr, with the final release to follow about a
fortnight after (assuming no major issues are found).

Hopefully, as many people as possible will be able to test the new
version of pip during the beta period (or before - it's possible to
install pip from github if you don't want to wait!) so that we can
ensure that pip 10 is as robust as we can manage when it gets
released.

There are a number of new features in pip 10, as well as many months
of bug fixes and minor improvements. Highlights include:

1. Support for PEP 518 (declaring build dependencies in `pyproject.toml`)
2. Fixes for Unicode handling in build tools (notably on Windows)
3. The previously announced reorganisation of pip's internals
4. A new `pip config` command
5. Default upgrade strategy becomes "only-if-needed"

Thanks to everyone who has contributed to this version of pip - it's
been a long time coming, and we apologise for the delay. The plan is
to ensure that future releases aren't delayed as long as this one was!

Paul