title: Add Time to a TDateTime
body: <p>I would like to add seconds to a <code>TDateTime</code> variable, so that the result is the top of the minute.  For example, if it's 08:30:25, I want change the <code>TDateTime</code> variable to store 08:31:00.</p>
  
  <p>I see that <code>TDateTime</code> has a Decode function, which I could use.  There isn't, however, an encode function to put the altered time back into a TDateTime variable.</p>