core, cmd, vendor: fixes and database inspection tool (#15)

* core, eth: some fixes for freezer

* vendor, core/rawdb, cmd/geth: add db inspector

* core, cmd/utils: check ancient store path forceily

* cmd/geth, common, core/rawdb: a few fixes

* cmd/geth: support windows file rename and fix rename error

* core: support ancient plugin

* core, cmd: streaming file copy

* cmd, consensus, core, tests: keep genesis in leveldb

* core: write txlookup during ancient init

* core: bump database version

cmd/utils/cmd.go

@@ -302,6 +302,8 @@ func ExportPreimages(db ethdb.Database, fn string) error {
 	}
 	// Iterate over the preimages and export them
 	it := db.NewIteratorWithPrefix([]byte("secure-key-"))
+	defer it.Release()
+
 	for it.Next() {
 		if err := rlp.Encode(writer, it.Value()); err != nil {
 			return err