title: Parse time data with subseconds
body: <p>I have some time data </p>
  
  <pre><code>01:09:00
  00:14:00
  00:00:00
  11:47:00
  10:34:00
  08:15:00
  </code></pre>
  
  <p>The data are measured in <code>%M:%S:00</code> (to the first numbers are the minutes, the second numbers are the seconds).  I would like to convert this into a total number of seconds.  This is easy to do with <code>lubridate</code> but R keeps thinking the format is in <code>%H:%M:%S</code>.  </p>
  
  <p>Can lubridate calculate the total number of seconds elapsed in the format my data are in? If not, how is the best way to transform the data into an appropriate format?</p>
  
  <p>I've thought about converting to character and just splicing out the minutes and seconds. </p>