SERVER-15541 MMAP v1 only takes LockMongoFilesShared for yielding plan executors
SERVER-16012 Rename heap1 to inMemoryExperiment
Don't check the time more than needed when locking
SERVER-16031 Call cleanShutdown rather than deleting KVEngines

Resolves some race conditions on shutdown.
SERVER-16026: on secnodaries w/doc locking, secondary unique indexes always have to be unchecked during batch
SERVER-16050: Do not sleep when yielding

Sleeping should not be necessary as ordering is purely determined
by the lock manager
SERVER-16048 Eliminate double copy and most ref-counting with RecordData
SERVER-16026 Improved combination of ns and _id field into hash value for worker thread selection.
Import wiredtiger-wiredtiger-2.4.0-293-g4e4bf47.tar.gz from wiredtiger branch develop
Don't log on first pass through lock wait loop
SERVER-16016 WiredTigerRecordStore::Iterator should not try to restore its state if it is EOF
SERVER-15645: clean up WiredTigerRecordStore::insertXXX
SERVER-15645: allow writes to oplog in IX by managing reads to block on oldest ts
SERVER-16046: only one thread should cleanup capped collections
Fix cache_size tuning error from commit:
1b446f240856cf93b32fcc62e1980d9cc2f42f87
SERVER-8511 prohibit local db and oplog collection from being dropped while replication is active
SERVER-16059 Fix integer truncation issues with timeouts

* No longer converting from us to ms since that truncated to 0 at <1000us.
* Assuming each call to wait() takes at least 1us.
SERVER-8511 Disable oplog dropping test in query_oplogreplay.js
SERVER-8511 move oplog-dropping test to noPassthrough suite
SERVER-16075 prefetch replication only on mmapv1