Hanappe sample scenes need onDestroy() examples

Hi, 

Could you review the 2 attached commits?  One commit turns on the MOAI histogram.  The other commit was my failing attempt to destroy a scene's resources.

This is not a traditional pull request. it is really just an issue but I couldn't figure out how to reference my branch 'check_memory' from a traditional github issue.  

It seems to me that each of the Hanappe sample scenes need an onDestroy() to clean up the props after a scene closes.  I'm am having trouble doing this, especially with the scroller example.  That example leaves a running coroutine as well as hundreds of existing props.  Any tips you could give? Thanks!