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.
Re-add extern.h, removed from git by accident.
Disable logging in test/salvage.
Always turn off logging in test/salvage (not just when verbose is set).
Merge branch 'develop' into fine-grained-durability.

Conflicts:
	src/include/txn.h
Merge branch 'develop' into fine-grained-durability

Conflicts:
	src/include/txn.h
Merge branch 'develop' into fine-grained-durability

Conflicts:
	src/include/extern.h
	src/txn/txn.c
Merge branch 'develop' into fine-grained-durability

Conflicts:
	src/txn/txn.c
Update dist/log.py to generate code to read and write log records.

--HG--
rename : src/log/log_desc.c => src/log/log_auto.c
Merge branch 'develop' into fine-grained-durability

Conflicts:
	src/conn/conn_ckpt.c
	src/conn/conn_log.c
	src/conn/conn_stat.c
Add auto-generated function to print log records.
Merge branch 'develop' into fine-grained-durability