Rename fletch -> dartino

src/vm/remembered_set.h

 // Copyright (c) 2016, the Dartino project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 #ifndef SRC_VM_REMEMBERED_SET_H_
 #define SRC_VM_REMEMBERED_SET_H_
 
-namespace fletch {
+namespace dartino {
 
 // TODO(erikcorry): Implement remembered set.
 class RememberedSet {
  public:
   inline void Insert(HeapObject* h) {}
 };
 
-}  // namespace fletch
+}  // namespace dartino
 
 #endif  // SRC_VM_REMEMBERED_SET_H_