Merges [tuna-f1sh/openant](https://github.com/tuna-f1sh/openant) that brings ANT+ device support, new CLI tools and generally brings up-to date. There some major changes to bring this to 1.0.0+:
* Python 2 support is dropped in favour of fully supporting Python 3.
* Module folder name changed to match module name 'ant' -> 'openant' in order to be more Pythonic. Symbolic link remains for legacy but should use `import openant`/`from openant.` from now on.
* Typing, docstrings and sphinx docs (needs further development).