Problem: estimates map can't write in parallel (#15)

Solution:
- change to slice

mvmemory.go

@@ -31,7 +31,7 @@ func NewMVMemory(
 
 func NewMVMemoryWithEstimates(
 	block_size int, stores map[storetypes.StoreKey]int,
-	storage MultiStore, scheduler *Scheduler, estimates map[int]MultiLocations,
+	storage MultiStore, scheduler *Scheduler, estimates []MultiLocations,
 ) *MVMemory {
 	data := make([]MVStore, len(stores))
 	for key, i := range stores {

stm.go

@@ -30,7 +30,7 @@ func ExecuteBlockWithEstimates(
 	stores map[storetypes.StoreKey]int,
 	storage MultiStore,
 	executors int,
-	estimates map[int]MultiLocations, // txn -> multi-locations
+	estimates []MultiLocations, // txn -> multi-locations
 	txExecutor TxExecutor,
 ) error {
 	if executors < 0 {