title: Sum two dates represented in a hh:mm:ss string format
body: <p>How can i put the 2 times together
  And i want it to stay in the time format: hh:mm:ss</p>
  
  <pre><code>string time1 = "00:49:35";
  string time2 = "00:31:34";
  
  totaltime = time1 + time2;
  </code></pre>
  
  <p>This should be the result
  01:21:09 (1 hour and 21 min and 09 sec)</p>