title: CCMenuItemImage - setSelectedImage and setNormal Image
body: <p>Ran across this while working with CCMenuItemImage. It seems like I have to set the SelectedImage and the NormalImage to different CCSprites, otherwise it crashes my application. (I plan on using unique assets later on for both states) CCMenuItemImage *ItemButton; is defined / initialized.</p>
  
  <p>The following does not work:</p>
  
  <pre><code>CCSprite *updatedSprite = [CCSprite spriteWithFile:@"1_button.png"];
  [ItemButton setNormalImage:updatedSprite];
  [ItemButton setSelectedImage:updatedSprite];
  </code></pre>
  
  <p>The following does work:</p>
  
  <pre><code>CCSprite *updatedSpriteNormal = [CCSprite spriteWithFile:@"1_button.png"];
  [ItemButton setNormalImage:updatedSpriteNormal];
  
  CCSprite *updatedSpriteSelected = [CCSprite spriteWithFile:@"1_button.png"];
  [ItemButton setSelectedImage:updatedSpriteSelected];
  </code></pre>
  
  <p>Curious to know why that would happen, I've done some digging but couldn't find anything definitive. Any insight would be great.</p>