Improved documentation of link() and rawlink()

Update to libuv 1.42.0

fixes #1851

Upgrade embedded c-ares to 1.18.1

Fixes #1847

Add pypy3.7 to Appveyor.

Fixes #1798.

Add test_signal for all versions.

Give up and disable test_signal on PyPy/Win. It hangs without running any tests.

Disable test__threading_vs_settrace on PyPy3/Appveyor. Somehow it fails to launch the script for unknown reasons.

.misc doesn't get put in the changelog by towncrier.

.misc doesn't get put in the changelog by towncrier.

Adding musllinux binary wheels and testing.

Update tested versions of PyPy

This is also 64-bit.

Update to testing 3.10.0 final

That's the latest that GHA currently has. We've been testing 3.10.0 on AppVeyor.

Updated 1814

Fix #1839 in a ham-fisted way.

There is probably a more elegant solution.

Unfortunately this drops 2.7 binaries because there is no image that has both. However, from pypistats.org, it appears that our Python 2 user base is finally under 10%.

Also removes the Google groups embedding from the main web page because that no longer works.

Fixes #1822

Patch libev and c-ares configure scripts for M1

This updates the config.sub and config.guess files
for libev and c-ares to the versions that are packaged
with automake 1.16.5. This pulls in a version compatible
with Apples aarch64 chip.

Update the appveyor download url for pypi2.7-v7.3.1

M1 uses arm64 as a cpu identifier. This is not understood
by the two configure scripts, but appears to work when patched.

manylinux: disable -ffast-math

See failed builds at https://github.com/gevent/gevent/pull/1820/checks?check_run_id=3807405865