Commit and checkpoint lsn flush.

[sanebay]

Commit and checkpoint lsn flush. From checkpoint lsn to latest, log replay should homeobject on commit, ignore any lsn from start lsn to checkpoint lsn.Any lsn between checkpoint to latest, may or might be there in btree. - Improvements.
solution 1: - Write to disk for every commit.
solution 2: - Batch it and commit and return to client.