~ 2 major bugfixes:
~ 1. investigation request shouldn't be made after only the journals got loaded, must delay till the segments got loaded too.
~ 2. LeafSegment#evaluateSizeAndNeedOfSplit & LeafSegment#notifyRemoval are merged into one: LeafSegment#evaluateEffectOfPut. There were exclusion of RemovalNotification, lack of use of `next` value to reduce lookups, and worst, repeated path walkthrough. Now gets all consolidated into one, and write perf is better.

as a result of consolidation, Put#suppressNotificationRemoval is saved, as Put#refreshes covers its scope.