Installation has been modernized to use setup.cfg for most package
metadata.

Fixes: #5404
Change-Id: Id59c0c4e7f81eca89999d1f1f8b03c89835a09d1

Start trying to convert fundamental objects to
C as we now rely on a fairly small core of things,
and 1.4 is having problems with complexity added being
slower than the performance gains we are trying to build in.

immutabledict here does seem to bench as twice as fast as the
Python one, see below.  However, it does not appear to be
used prominently enough to make any dent in the performance
tests.

at the very least it may provide us some more lift-and-copy
code for more C extensions.

import timeit

from sqlalchemy.util._collections import not_immutabledict, immutabledict

def run(dict_cls):
    for i in range(1000000):
        d1 = dict_cls({"x": 5, "y": 4})

        d2 = d1.union({"x": 17, "new key": "some other value"}, None)

        assert list(d2) == ["x", "y", "new key"]

print(
    timeit.timeit(
        "run(d)", "from __main__ import run, not_immutabledict as d", number=1
    )
)
print(
    timeit.timeit(
        "run(d)", "from __main__ import run, immutabledict as d", number=1
    )
)

output:

python: 1.8799766399897635
C code: 0.8880784640205093

Change-Id: I29e7104dc21dcc7cdf895bf274003af2e219bf6d

Also remove no longer used compat code

Change-Id: Ifda239fd84b425e43f4028cb55a5b3b8efa4dfc6

- Fix typo in resultproxy.c that would error on windows.
- add -Wundef to C flags when linux is detected so that undefined
symbols emit a warning
- a few adjustments for tests to succeed on python 3.5
- note minimum version still documented here as 3.4 but this should
move to at least 3.5 if not 3.6 for SQLAlchemy 1.4

Change-Id: Ia93ee1cb5c52e51e72eb0a24c100421c5157d04b

Fixes: #5113

<!-- Provide a general summary of your proposed changes in the Title field above -->

### Description
Add py3.8 and py3.9 tokens to setup.py

### Checklist
<!-- go over following points. check them with an `x` if they do apply, (they turn into clickable checkboxes once the PR is submitted, so no need to do everything at once)

-->

This pull request is:

- [ ] A documentation / typographical error fix
	- Good to go, no issue or tests are needed
- [x] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

**Have a nice day!**

Closes: #5115
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5115
Pull-request-sha: 5ae662f1ec0d89a16a03fe60d6f12712d0d21398

Change-Id: I1313df9bd117b1356c1d06d588e8e04a07ba4e39

The C extensions have been broken since cc718cccc0bf8a01abdf4068c
however CI did not find this, because the build degraded to
non-C extensions without failing.   Ensure that if cext is set,
there is no fallback to non-cext build if the C extension build
fails.

Repair C related issues introduced in cc718cccc0bf8a01abdf4068c.

As C extensions have been silently failing on 2.7 for some commits,
the callcounts also needed to be adjusted for recent performance-related
changes.  That in turn required a fix to the profiling decorator
to use signature rewriting in order to support py.test's
fixture mechanism under Python 2, usage introduced under profiling
in 89bf6d80a9.

Fixes: #5076
Change-Id: Id968f10c85d6bf489298b1c318a1f869ad3e7d80

Added a workaround for a setuptools-related failure that has been observed
as occurring on Windows installations, where setuptools is not correctly
reporting a build error when the MSVC build dependencies are not installed
and therefore not allowing graceful degradation into non C extensions
builds.

Setuptools issue https://github.com/pypa/setuptools/issues/1902

Fixes: #4967
Change-Id: I5e21e7e78cb6d927b18afce64cacf8643b98354e

general README.unittest.rst edits

Fixes: #4789
Fixes: #4900
Change-Id: Ifddd3bfd1e6a4d24d3b0a3e1702e04e66a42a4dd

While we have the OSI classifier for "MIT License", it looks
like for the "license" field, this is normally just the word
"MIT" and not "MIT License".   While the pypa docs suggest we
only need it as the OSI classifier, keep it also in "license"
in order to appease common tooling.

Change-Id: Ife51bbc74d6c1b8ab9a736024818fbba35316e17

Change-Id: I379b3d9e59ff8cda17c2d738fde794249f105510