Remove tab characters.
Add a new field to the WT_CURSOR_BTREE structure so we can pass back a
reference to the modify function's allocated update structure, avoids a
potential data copy when changing the user's cursor to point to internal
data.  Closes #1070.
Add support for random isolation configurations, where each new session
is assigned one of the possible isolation settings at random.
Merge branch 'develop' into debug-lsm-dirty-after-checkpoint