Made (Un)PackCaloHypo half way functional
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Goes with Rec!2266 (merged), Moore!666 (merged) and DaVinci!474 (merged)
To be precise PackCaloHypo is functional for its output, but not for its input. This would need producers of the input to be functional too. Left for next round.
Also cleans up the interface ClusterFromHypo, using references rather than pointers