Add `build-system.requires` key to `pyproject.toml`:
- this is necessary with pip 10.0.1, as otherwise the defaults will be
  to require both `setuptools` and `wheel` (and we only need the later)
- a `pyproject.toml` with no `build-system.requires` key will be invalid
  and rejected by a future version of pip
  (see https://github.com/pypa/pip/issues/5416#issuecomment-399638608)

Avoid resource warning from dev scripts installed editable

Avoid ` ResourceWarning: unclosed file <_io.TextIOWrapper name='whatever' mode='r' encoding='UTF-8'>` on dev scripts installed editable

Fix Town Crier Link

Apparently when specifying any doctest_optionflags, it's necessary to also indicate the defaults. Add ELLIPSIS to fix other failing tests.

Remove documentation about non-package data files that's no longer relevant without eggs. Fixes #1385.

Drop support for EOL Python 3.3

Add reference to Setuptools Developers team for clarity of maintenance and removed reference to Jason as maintainer.