Remove Start() check from WriteTxn()

It is often useful, especially in tests, to be able to populate the tables
before starting the application. While it is useful to check that the
DB has been started (e.g. graveyard GC is running), it's currently too
inconvenient to disallow using of the database before starting it.

Signed-off-by: Jussi Maki <[email protected]>

db.go

@@ -244,10 +244,6 @@ type Handle struct {
 }
 
 func (h Handle) WriteTxn(table TableMeta, tables ...TableMeta) WriteTxn {
-	if h.db.gcTrigger == nil {
-		panic("Database has not been started with Start()")
-	}
-
 	db := h.db
 	allTables := append(tables, table)
 	smus := internal.SortableMutexes{}