Python bindings for CLIPS 6.40

[noxdafox]

`CLIPSPy` `1.0.0` has been released.

This version is based on CLIPS 6.40.

The APIs have been refactored based on the learnings with CLIPS 6.30 and to better reflect the changes in the C ones. Test coverage has also been increased.

Python 2 support has been dropped and the minimum supported Python version is now 3.6.

`iCLIPS` as well has been ported to the new library version.

`clipspy`: https://pypi.org/project/clipspy/
`iCLIPS`: https://pypi.org/project/iCLIPS/

Big thanks to Gary Riley for releasing CLIPS 6.40!