Add isReachable API to IMessageRecipient.

Add translatable message recentlyForeverAlone.
Add behaviour that preserves reply-recipient only if they are reachable, and update reply-recipient if they are not reachable.
Fixes #248

Essentials/src/com/earth2me/essentials/Console.java

@@ -50,6 +50,10 @@ public final class Console implements IMessageRecipient {
     @Override public void sendMessage(String message) {
         getCommandSender().sendMessage(message);
     }
+
+    @Override public boolean isReachable() {
+        return true;
+    }
     
     /* ================================
      * >> DELEGATE METHODS