title: trim phone number with regex
body: <p>Probably an easy regex question.</p>
  
  <p>How do I remove all non-digts except leading + from a phone number?</p>
  
  <p>i.e. </p>
  
  <p>012-3456 => 0123456<br>
  +1 (234) 56789 => +123456789</p>