title: how to cancel a timer when using timerManager in veins omnet
body: <p>I'm using TimerManager class provided in veins to manage timers in my simulation.
  I created a recurring timer that fires every 5 seconds and I want to cancel it when a specific msg is received but I don't know how to use the cancel method:</p>
  
  <p><code>void cancel(TimerHandle handle)</code></p>
  
  <p>I don't understand what is TimerHandle and what parameter should I pass to the method in order to cancel the timer </p>
  
  <p>PS:i want to cancel a specific timer not the TimerManager instance</p>