title: Can't compile nested less files with Web Compiler 2015
body: <p>well, I was quite surprised when installing Web Essentials 2015 for Visual Studio 2015 that it didn't include a less compiler anymore: 
  "Web Essentials 2015 no longer contains features for bundling and minifying of JS, CSS and HTML files as well as compiling LESS". </p>
  
  <p>Everything worked fine before with Visual Studio 2013. So I downloaded Web Compiler 2015, as it is the new compiler from Mads Kristensen. But, after adding all the needed files to be compiled to the compilerconfig.json, I have an error on compilation that it doesn't recognize my variables anymore nor my mixins!</p>
  
  <p>Here's my site.less:</p>
  
  <pre><code>/* Colors and common variables */
  @import "Colors";
  @import "Variables";
  
  /* Reseting default values for all internet browsers */
  @import "Reset.css";
  
  /*  BootStrap   */
  @import "../../../Content/bootstrap/bootstrap.less";
  
  /* Basic mixins */
  @import "mixins/Generic_Mixin.less";
  @import "mixins/Controls.less";
  @import "mixins/Images.less";
  @import "mixins/Navigation.less";
  @import "mixins/Text.less";
  
  /* Website specific classes */
  @import "Controls.less";
  @import "Footer.less";
  @import "Header.less";
  @import "Images.less";
  @import "Text.less";
  @import "combobox.less";
  
  @import "Sitemaster.less";
  </code></pre>
  
  <p>And here's one of my many errors :</p>
  
  <pre><code>variable @font-size-base is undefined on line 49 in file
  'C:\Users\(...)\Site.WebApp\App_Themes\Default\Styles\mixins\Variables.less':
  </code></pre>
  
  <p>Please, I don't understand anything to all of this, anyone would have an answer for me ? Thx.</p>