Test fine-grained durability in test_txn02.
Add structures and encoding / decoding for fine-grained durability.
Add logging for transaction commits.
Add support for "wt printlog" for the new transactional logging code.
Implement basic transactional recovery.
Put in the hook to run recovery when existing logs are opened.
Add support for recovery of remove operations and column stores.
Optimize key return: always take the key if the cursor references a WT_INSERT.
Speed up tests by allowing smaller log files (100K) and using them.