v0.9-alpha - useful, but not well tested

This is a first pre-relase of my pure Pyhon Chess implementation.
It was designed to be elastic and be able to easily implement other chess variants, even like four-player chess and three dimensional chess.
But for now only Classic, King of The Hill and Three Check are fully implemented.
In fact there is almost no tests, one test that makes me to do this pre-relase was something arround one thousand fast stockfish-stockfish games (it's a chess engine) where no error occurred. Of course there is a few bugs but nothing that impact game logic (as far as I tested).

In the final v1.0 relase proper tests will appear, and I think almost all of @property decorators will disappear as well.