Add code to confirm Michael's idea on the #682 failure.
Merge branch 'develop' into branch682
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.
Semantic sugar.

Inline __wt_cache_bytes_dirty() and __wt_cache_pages_dirty(), there's no
policy of not directly accessing WT_CACHE fields, and that's all they do.

Remove comments about 8B vs. 4B atomic read/write and "special" code in
__wt_cache_pages_inuse() and __wt_cache_bytes_inuse(), WiredTiger
requires 8B atomic read/write, the comments no longer make any sense.
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 branch682
Michael fixed the real problem in #682; remove the test code, but leave
the change that supports discarding a clean internal node with children;
I'm not sure we're going to keep it, though.
A different fix/change: return from __rec_review() if the page being
evicted is the top page of a tree of pages.  That avoids the additional
cost of walking an internal page with no in-memory children in both the
clean and dirty cases (so it's marginally faster), and won't break if
we ever evict clean nodes with children in the future.