title: how to split array into n groups? (factorize, or _.partition array)
body: <p>Let's say I have an array = [0,1,2,3,4,5,6] and I want to "partition" it into 3 arrays, based on reminder after division by 3.</p>
  
  <p>so basically I'd want something like:</p>
  
  <pre><code>_.my_partition([0,1,2,3,4,5,6], function(item) {return item % 3;})
  // [[0,3,6], [1,4],[2,5]]
  </code></pre>
  
  <p>(I can use lodash, underscore, if ti helps...)</p>