title: Preparing plugin for $.plugin() usage instead of $(selector).plugin()
body: <p>Simply:</p>
  
  <pre><code>(function($){
      $.fn.plugin = function()
      {
          // results in error
          // when called like
          // $.plugin();
      }
  })(jQuery);
  </code></pre>
  
  <p>The error is (copied from Chrome console): </p>
  
  <pre><code>Uncaught TypeError: Object function ( selector, context ) {
          // The jQuery object is actually just the init constructor 'enhanced'
          return new jQuery.fn.init( selector, context, rootjQuery );
      } has no method 'plugin'
  </code></pre>
  
  <p>What rules I have to follow in order to make my plugin work without the element selection?</p>