Updated server shutdown timer logic

Will follow the following rules

+ send a message initially
+ send a message every 20 mins
+ send a message every min when time <= 5

Updated client popup

Updated client to close any previous popups and bring up a new one.

NEEDS TO BE TESTED

added missing include

Added delete on close

cockatrice/src/window_main.h

@@ -31,6 +31,7 @@ class LocalClient;
 class LocalServer;
 class ServerInfo_User;
 class QThread;
+class QMessageBox;
 
 class MainWindow : public QMainWindow {
     Q_OBJECT
@@ -86,6 +87,8 @@ private:
     
     LocalServer *localServer;
     bool bHasActivated;
+
+    QMessageBox *serverShutdownMessageBox;
 public:
     MainWindow(QWidget *parent = 0);
     ~MainWindow();