Corrected Match cancellation.

It was using the old QUIT command.
Adjusted ignored files.

* NPM & Bower installed components.
* Documentation generated with Docker.
DIRECTIONS should be a class property.
Improved Othello.

* Changed constructor to allow the board to be serialized.
* Fixed and optimized move generation.
* Playtester runs MCTS players in web workers.
* Better looks in playtester with SVG+CSS instead of symbol characters.