#33 Scheduling sync

[Zijian]

1. Regularly sync every 5 minutes or longer interval.

Optionally show the sync window, or just show a tooltip in Windows tray, kind of background operation.

[Zijian]

need to do further decoupling business codes from UI codes, for this one and #32.

   void SyncAll()
    {
        foreach (Control control in panel1.Controls)
        {
            UcSync syncUc = control as UcSync;
            //Debug.Assert(syncUc != null, "What, not syncUc?");
            if (syncUc == null) //could be the status box
                continue;

            IAsyncResult r = syncUc.Sync();
            while (!r.IsCompleted)
            {
                System.Threading.Thread.Sleep(200);
            }

        }
    }