Re-fixed cascading support

cascading color/opacity is working OK, and can be enabled / disabled
with the  `node.cascadeColor` and `node.cascadeOpactiy` properties.

Those properties are disabled by default in all nodes except in:
 - CCMenu (propages opacity/color to its children)
 - CCMenuItemImage (propagates opacity/color to the image)
 - CCLabelBMFont (propagates opacity/color to the letters)