Last irreversible block and other small fixes
[Fix] Workaround for inconsistency in AH data after reindex (data was pushed directly as irreversible but state thinks some blocks are still reversible)
[Fix] Block api no longer gives blocks that were not processed into state even if longer block_log is available.
[Fix] hived compiles again with SMTs enabled.
[Ign] Cleaning old marked history data now follows the same pattern as everything else (with object reference instead of iterator copy - just in case).
Supplemented comment on how we can workaround problem of steem recovery account.