Wait some grace period between two subsequent transfers.

Closes #9

ATxService/AutoTx.cs

@@ -32,6 +32,7 @@ namespace ATxService
         private RoboCommand _roboCommand;
         private long _txCurFileSize;
         private int _txCurFileProgress;
+        private int _waitCyclesBeforeNextTx;
 
         private DateTime _lastUserDirCheck = DateTime.MinValue;
 
@@ -579,6 +580,14 @@ namespace ATxService
                 return;
             }
 
+            // give the system some time before starting the next transfer:
+            if (_waitCyclesBeforeNextTx > 0) {
+                Log.Debug("Waiting {0} more cycles before starting the next transfer...",
+                    _waitCyclesBeforeNextTx);
+                _waitCyclesBeforeNextTx--;
+                return;
+            }
+
             // dispatch the next directory from "processing" for transfer:
             try {
                 StartTransfer(subdirs[0].FullName);

ATxService/RoboCommand.cs

@@ -164,6 +164,7 @@ namespace ATxService
             _txCurFileProgress = 0;
             _roboCommand.Dispose();
             _status.TransferInProgress = false;
+            _waitCyclesBeforeNextTx = 2;
         }
 
         /// <summary>