more operations;

--- a/src/Pure/General/sqlite.scala	Tue Sep 06 21:09:18 2016 +0200
+++ b/src/Pure/General/sqlite.scala	Tue Sep 06 21:17:33 2016 +0200
@@ -29,6 +29,8 @@
 
     def close { connection.close }
 
+    def rebuild { using(statement("VACUUM"))(_.execute()) }
+
     def transaction[A](body: => A): A =
     {
       val auto_commit = connection.getAutoCommit