Split general WT_BTREE fields into WT_DATA_HANDLE.
Rename {conn,session}_btree.c to {conn,session}_dhandle.c.

--HG--
rename : src/conn/conn_btree.c => src/conn/conn_dhandle.c
rename : src/session/session_btree.c => src/session/session_dhandle.c
Replace session->btree with a data handle.
Merge branch 'develop' into data-handles

Conflicts:
	src/btree/rec_write.c
	src/conn/conn_dhandle.c
	src/cursor/cur_index.c
	src/schema/schema_drop.c
Merge branch 'develop' into data-handles

Conflicts:
	src/btree/bt_handle.c
	src/conn/conn_dhandle.c
	src/cursor/cur_file.c
	src/include/btree.h
	src/include/cache.i
	src/include/extern.h
	src/lsm/lsm_worker.c
	src/session/session_dhandle.c
	src/support/hazard.c
Merge branch 'develop' into data-handles

Conflicts:
	src/btree/bt_evict.c
Merge branch 'develop' into data-handles

Conflicts:
	dist/filelist
	src/block/block_mgr.c
	src/btree/bt_cell.c
	src/btree/bt_curnext.c
	src/btree/bt_curprev.c
	src/btree/bt_debug.c
	src/btree/bt_evict.c
	src/btree/bt_handle.c
	src/btree/bt_slvg.c
	src/btree/bt_stat.c
	src/btree/bt_vrfy.c
	src/btree/bt_vrfy_dsk.c
	src/btree/rec_write.c
	src/btree/row_srch.c
	src/conn/conn_dhandle.c
	src/cursor/cur_file.c
	src/cursor/cur_index.c
	src/cursor/cur_stat.c
	src/include/api.h
	src/include/btree.h
	src/include/btree.i
	src/include/cache.i
	src/include/extern.h
	src/include/serial.i
	src/include/stat.h
	src/include/wt_internal.h
	src/lsm/lsm_cursor.c
	src/lsm/lsm_worker.c
	src/meta/meta_track.c
	src/schema/schema_drop.c
	src/schema/schema_plan.c
	src/schema/schema_truncate.c
	src/session/session_api.c
	src/session/session_dhandle.c
	src/txn/txn_ckpt.c
Merge branch 'develop' into data-handles

Conflicts:
	src/btree/bt_evict.c
	src/btree/bt_handle.c
	src/btree/bt_page.c
	src/btree/rec_evict.c
	src/conn/conn_dhandle.c
	src/cursor/cur_stat.c
	src/include/btree.h
	src/include/btree.i
	src/include/stat.h
	src/lsm/lsm_cursor.c
	src/schema/schema_create.c
	src/txn/txn_ckpt.c
Merge branch 'develop' into data-handles
Update new code to use data handles.
Merge branch 'develop' into data-handles
Minor fixes for data handles: fix loop termination in eviction, remove obsolete files, cleanups for s_all.
Track cursor creation in the statistics (as demonstrated by the Basho
benchmarks, creating a cursor per operation isn't a good idea).
Merge branch 'develop' into data-handles
Merge branch 'develop' into data-handles
update a comment
Move WT_DATA_HANDLE into its own header file (dhandle.h).

--HG--
rename : src/include/btree.h => src/include/dhandle.h
Merge pull request #494 from wiredtiger/data-handles

Split out a generic "data handle" from btrees for caching and locking.