CCMaskTo
============

CCMaskTo is a CCIntervalAction for cocos2d-iphone written by georgejcook and slightly modified by taberrr to work with cocos2d v0.99.3-rc.

http://www.cocos2d-iphone.org/forum/topic/1306#post-7891

  Usage:

  //
  // Reveal the sprite in a "swipe from left" style mask transition
  //
  CCSprite *mySprite = [CCSprite spriteWithTexture: spriteSheet.texture rect: CGRectMake(0,0, 1,10)];
  [spriteSheet addChild: mySprite];
  mySprite.position = ccp(screenSize.width / 2 - 45, screenSize.height / 2);

  [mySprite runAction: [CCMoveBy actionWithDuration: 1 position: ccp(45, 0)]];
  [mySprite runAction: [CCMaskTo actionWithDuration: 1 rect: CGRectMake(0,0, 90,10)];