Rename fletch -> dartino

src/vm/message_mailbox.cc

Index: src/vm/message_mailbox.cc
diff --git a/src/vm/message_mailbox.cc b/src/vm/message_mailbox.cc
index ef899795511aa2807297ed9d15d14f3e468d1afe..b90d589519cdfe9bd0d62b883bedca1955bd580b 100644
--- a/src/vm/message_mailbox.cc
+++ b/src/vm/message_mailbox.cc
@@ -5,7 +5,7 @@
 #include "src/vm/message_mailbox.h"
 #include "src/vm/process.h"
 
-namespace fletch {
+namespace dartino {
 
 ExitReference::ExitReference(Object* message) : message_(message) {}
 
@@ -55,4 +55,4 @@ void MessageMailbox::EnqueueExit(Process* sender, Port* port, Object* message) {
   EnqueueEntry(entry);
 }
 
-}  // namespace fletch
+}  // namespace dartino