update to the current Memrata design.
Rewrite S2BT to avoid lots of "dereference of a null pointer" warnings from clang-analyzer.
Cleanup: __wt_update_check() has lost most of its functionality over
time, replace it with calls to __wt_txn_update_check, and remove the
calls entirely when there's no WT_UPDATE structure and so no possibility
of detecting a collision.
Remove "Memrata" doc link from the top-level navigation.
Cut release 1.6.4
Bump release version on develop branch to 1.6.5
Fix some clang "dead assignment" warnings.
Merge pull request #632 from wiredtiger/clang-analyzer-warnings

Fix some clang-analyzer warnings
added *.wtperf files for Jenkins perf runs, removed small.wtperf.  refs #593

also removed small.wtperf.
added new option 'transaction_config'. help message formatting. refs #593
Add transaction isolation configuration to another place in wtperf.
General support for recovery of Memrata/KVS devices.
typo
lint
Merge branch 'develop' into fine-grained-durability