Add constant for escape key being pressed, used by many games to display a menu and/or pause the game.
Add constant for escape key being pressed, used by many games to display a menu and/or pause the game.

GameJs/gamejs,jrburga/jsvgdl,GameJs/gamejs,GameJs/gamejs,jrburga/jsvgdl,jrburga/jsvgdl,jrburga/jsvgdl