Decaching old core messages

[pfrazee]

SFW maintains its own index of changes which it can query. This means that checking the history of file operations can be accomplished with the "latest" index bee. It might be possible to locally decache the index core's messages which are no longer needed to construct the latest state, reducing overall disk usage. This depends on what Autobase depends on, which I'm still learning about.

Input cores might also be able to decache messages, but this is less clear to me as remote indexers may still require those messages.