Fixes issue 3425: Enter in NSD still occasionally opens two servers

Change-Id: I6b4296ccf660940cb9a7173ee6bd31b2fa87fe3e
Reviewed-on: http://gerrit.dmdirc.com/295
Tested-by: Gregory Holmes <greboid@dmdirc.com>
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>

src/com/dmdirc/addons/ui_swing/dialogs/NewServerDialog.java

     private JButton editProfileButton;
     /** Main frame. */
     private MainFrame mainFrame;
+    /**  Opening new server? */
+    private boolean openingServer = false;
 
     /**
      * Creates a new instance of the dialog.
      * Saves the dialog changes.
      */
     private void save() {
+        if (openingServer) {
+            dispose();
+            return;
+        }
         if (!serverField.validateText()) {
             serverField.requestFocusInWindow();
             return;
         final int port = Integer.parseInt(portField.getText());
 
         dispose();
+        openingServer = true;
 
         final Identity profile =
                 (Identity) identityField.getSelectedItem();