Pycmx

- Updated the project to use online github online testing/integration.
- Support for Python 2.7 and 3.5 has been removed.
- Several minor lint fixes.

New release workflow.

Added Python 3.7 to tests

Also some documentation and code style tweaks.

* Documentation
* An interface tweak: we no longer accept paths, but accept file handles, which is more conventional.
* Tests.

Also an example program: `edl2scenelist.py` for creating scene lists from EDLs.