title: chron write to string and back
body: <p>(New to R, and coming from the world of pandas) </p>
  
  <p>Assuming I have a column of chron objects in my data frame, how is it that I might be able to write them to csv in the right format, such that when I read back the csv, I can convert the same column back into chron objects as easily as <code>pandas.to_datetime(df.dt_col)</code>?  </p>
  
  <pre><code>&gt; x = chron("10/19/15", "22:11:22")
  &gt; x
  [1] (10/19/15 22:11:22)
  &gt; as.character(x)
  [1] "(10/19/15 22:11:22)"
  &gt; as.chron(as.character(x))
  Error in as.POSIXlt.character(x, tz, ...) : 
    character string is not in a standard unambiguous format
  </code></pre>