title: Convert months mmm to numeric
body: <p>I have been given a csv with a column called month as a char variable with the first three letters of the month. E.g.:</p>
  
  <pre><code>"Jan", "Feb","Mar",..."Dec"
  </code></pre>
  
  <p>Is there any way to convert this to a numeric representation of the month, 1 to 12, or even a type that is in a date format?</p>