Any bytes we can skip in a parent page, we can skip in a child page,
the keys are going to have the same set of prefixes.   Ref #595.
Add a reference count to LSM chunks, so that chunks can't be freed
while worker threads are accessing them.
Write lock around refcnt changes.
Don't decrement LSM chunks that have been free'd.
Fix a bug in LSM chunk reference counting on shutdown.
Merge branch 'develop' into lsm_worker_refcount
Merge branch 'develop' into offsetsearch2
Merge pull request #696 from wiredtiger/lsm_worker_refcount

Add a reference count to LSM chunks
lint
Merge pull request #694 from wiredtiger/offsetsearch2

skip the same prefix bytes on the child page that we skipped on the parent page
Change the default statistics_fast configuration from false to true.
Fix a race when walking trees for eviction.

Don't switch a page's state to WT_REF_MEM until after we have finished looking
inside its WT_PAGE struct -- another could come in and evict it in between.

refs #682
Add more commentary about the snap_min value published for read-uncommitted operations.  Switch to using the last oldest value: I think that's more obviously correct.

refs #691
Merge pull request #682 from wiredtiger/evict-walk-race

wtperf failure: accessing a freed page
Merge branch 'develop' into cache-dirty-bytes