I took a while to figure out why coverage wasn't working correctly for our large project until yesterday, when I read the paragraph that called out the `.coveragerc` options that `pytest-cov` ignores.  

This PR makes that part of the documentation "pop" a bit more.

I considered moving it under "Caveats", but decided that that would mean rewriting "Caveats" to have two separate issues, rather than the one that it currently explains.

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

The empty 'console_scripts' entry point serves no purpose, and it is
rather unlikely for it to contain any script in the near future.  Its
presence confuses Gentoo missing dependency checks.

Fix custom commands to handle additional arguments to the run() method.
This is needed with newer versions of setuptools since they've started
passing 'show_deprecation' kwarg in easy_install command, and this
resulted in the following error:

```
Traceback (most recent call last):
  File "/tmp/pytest-cov/./setup.py", line 86, in <module>
    setup(
  File "/usr/lib/python3.9/site-packages/setuptools/__init__.py", line 153, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib/python3.9/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/usr/lib/python3.9/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/usr/lib/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/usr/lib/python3.9/site-packages/setuptools/command/install.py", line 67, in run
    self.do_egg_install()
  File "/usr/lib/python3.9/site-packages/setuptools/command/install.py", line 117, in do_egg_install
    cmd.run(show_deprecation=False)
TypeError: run() got an unexpected keyword argument 'show_deprecation'
```

While at it, future-proof all overriden commands to accept pass any
arguments through.

* added toml extra

* Update AUTHORS.rst

* Update CHANGELOG.rst

* chain toml dependency to coverage's toml dependency

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

* move coverage's toml dependency from extras to install_requires

* udpate changelog phrase

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

Fixes: #557