title: Bootstrap 3.1 How to use mixin make-grid-columns()?
body: <p>I used to use Bootstrap 3.0, and compiled my css from the bootstrap less files + some of my own less.</p>
  
  <p>In this some of my classes adopts some bootstrap styles like this:</p>
  
  <pre><code>.myClass{
      .col-md-3;
      border: 1px solid #000;
      [etc, etc]
  }
  </code></pre>
  
  <p>It worked out great in Bootstrap 3.0, since all col-md-X classes are defined as less variables. But in Bootstrap 3.1 this seems to be somehow replaced with a mixin function called make-grid-columns().</p>
  
  <p>Does anybody know how to utilize this mixin, and how to port the construction above into Bootstrap 3.1? :-/</p>