Third version uploaded

Uploaded the third version of my checkers.

Added:

* Start/end game animation.

* Restart possibility.

* Promotion animation.

Plans for the future:

* Wrong move animation (highlight mandatory capture).

* Fix drag'n'drop.

* Add touchscreen support.

* Fix ugly scaling/aliasing issues.

* Add captured stones counter (?).

* Add current player indicator.

* Enable undoing moves.

* Add AI with difficulty slider.