title: PHP replace all characters with asterisk
body: <p>So lets say I have a password in the form of a string:</p>
  
  <pre><code>$password = "thisisaplaintextpassword"
  </code></pre>
  
  <p>How can I turn it into the following?</p>
  
  <pre><code>$password = "************************"
  </code></pre>
  
  <p>I would like to send users their account details via email, and don't want to send the entire thing.</p>