title: Count repeated letters in a string
body: <p>I'm stuck with the following problem:
  I need to  find repeated characters in a string.
  Basically what I want is regular expression that will match like that</p>
  
  <pre><code>hello - ["ll"];
  here  - ["ee"];
  happiness   -  ["pp","ss"];
  pupil  -  ["pp"];
  </code></pre>
  
  <p>I have the one that matches consecutive repeated characters</p>
  
  <pre><code>  /([a-z])\1+/g
  </code></pre>
  
  <p>Also the one that will match repeated chars and everything  between them like  this one</p>
  
  <pre><code>   /([a-z])(?:.*)\1+/g
  </code></pre>
  
  <p>But cant figure out the correct one.</p>