Updated to use Object.create() instead of the constructor pattern for modules. Much cleaner code and more simplistic inheritance.
If the module has a constructor, you will need to call it's init() method with the desired parameters.

Example:

Old way

var mySpriteSheet = new lithium.Resource.SpriteSheet("image.gif", 5, 5, 0);

New way
var mySpriteSheet = Object.create(lithium.Resource.SpriteSheet);
mySpriteSheet.init("image.gif", 5, 5, 0);

This of course does add more code to write for implementors, but there should be a more coherent API before we hit production, so consider it a work in progress.
The amount that it simplifies inheritance and overall module complexity is well worth any extra sauce we have to add to the API