* Added Best Score, with local properties file to store it. It increases when the score is greater than the former best score.
* Added clock to show elapsed time. 
* Added pause control (key P) and white overlay to nearly cover the tiles, showing two buttons (Keep Going and Try Again) to resume the game or start a new one. 

Timer stops during pause or when 2048 tile is reached. It goes on after Keep Going button is clicked. It restarts if Try Again button is clicked.
* Added resizable capabilities: the stage starts at maximum visible size of the primary screen, keeping the aspect ratio of the game. 
Then it can be resized, to any bigger or smaller size (up to half size of the actual game dimensions).
* Fixed dropshadow effect problem: with bigger radius, the effect moves the game, and in the Raspberry Pi this could even cause exceptions. By adding a rectangle to clip the grid, all the effects are applied within the grid.
* Fixed points location when scaling up or down the scene.
* Added resizable capabilities: the stage starts at maximum visible size of the primary screen, keeping the aspect ratio of the game. 
Then it can be resized, to any bigger or smaller size (up to half size of the actual game dimensions).
* Fixed dropshadow effect problem: with bigger radius, the effect moves the game, and in the Raspberry Pi this could even cause exceptions. By adding a rectangle to clip the grid, all the effects are applied within the grid.
* Fixed points location when scaling up or down the scene.
Merge pull request #17 from jperedadnr/master

* Added Best Score, Clock and Pause
* Added resizable capabilities