js game engine

##Version 0.2.5

• MemoryCard
  • Can save a string or a object

##Version 0.2

• Added Sound class
  • User can now preload a sound
• Added SpriteSheet class
• Added TextField class
• Added Group class
• Added demos:
  • Space Invaders;
  • SpriteSheet
  • Sokoban
• Improve Scene class
• Added background color property to Surface class

##Version 0.1.5

• collision by point, box and pixel
• Tween Animation