2i order of events

When running a load of mainly 2i queries, there is a huge cost in the
previous snapshot code.  The time taken to create a clone of the
Penciller (duplicating all the LoopState) varied between 1 and 200ms
depedning on the size of the LoopState.

For 2i queries, most of that LoopState was then being thrown away after
running the query against the levelzero_cache.  This was taking < 1ms on
average.  It would be better to avoid the o(100)ms of CPU  burning and
block for o(1)ms - so th eorder of events have been changed ot filter
first so only the small part of the LoopState actually required is
copied to the clone.

include/leveled.hrl

@@ -54,6 +54,8 @@
                         {root_path :: string(),
                         max_inmemory_tablesize :: integer(),
                         start_snapshot = false :: boolean(),
+                        snapshot_query,
+                        bookies_mem :: tuple(),
                         source_penciller :: pid(),
                         levelzero_cointoss = false :: boolean()}).