history log messages on edit of measure criteria
removed IObjectAddedEvent subscriber -- there was no need to call handle_measure_modify (for cache purposes) on newly created measure, as it will not have any cached informtion to invalidate or reload.
Cache built queries for numerator, denominator for measure, rather than do it per-datapoint, which is duplicative; invalidation is done by resetting all volatiles and flagging measure definition as changed for ZODB within a modification handler, which also invallidates IComposedQuery lookup caching.