Font-line

- bump fonttools dependency to v4.17.0
- update setup.py classifiers to remove Py2.7, Py < 3.6
- update setup.py classifiers to include Py 3.7, 3.8, 3.9
- remove docs/README.rst (no longer used for PyPI release documentation and not maintained)

- add cPython 3.9 unit testing
- add CodeQL static source code testing
- update fonttools dependency to v4.16.1

- adjust line length to < 90
- transition to GitHub Actions CI testing service
- update fonttools dependency to v4.14.0

- remove Py2 wheels

- add requirements.txt file with pinned dependency versions
- update all build dependencies to current release versions
- the fontTools dependency updates add support for Unicode 13
- convert PyPI documentation to repository README Markdown file
- add Py3.8 interpreter to CI testing

- added baseline to baseline distance calculations for hhea, typo, and win metrics to reports
- added fsSelection bit 7 `USE_TYPO_METRICS` bit flag setting to report
- standard output report formatting improvements for `report` subcommand
- removed Py3.5 interpreter testing, we will support for Py3.6+ only as of this release
- add support for automated source code coverage push to Codecov from Travis