ADDITION:

	(*) Introducing ClusterAnaPrep module
	    - Its purpose is to loop over clusters & associated hits to extract cluster-wise information that is useful for various analysis.
	    - It is a singleton class: other modules can call this analysis unit from any function through a static ClusterAnaPrep::get() method.
	    - Upon running analyze() method, it checks run, subrun, and event id of the provided event. If the event is already processed, it returns immediately w/o doing anything.

-Kazu