Member turns to undefined
<p>I've developed a jQuery plugin which has default options:</p>

<pre><code>$.fn.incromentor.defaults = {
   max : 65355,
   min : 0
};
</code></pre>

<p>In the initialization of the plugin, I merge the user options with plugin default options using <code>$.extend</code></p>

<pre><code>function init( $elm, options )
{
    this.$element = $elm;
    this.options = $.extend( {}, $.fn.incromentor.defaults, options ); 
}
</code></pre>

<p>So the problem is, if user sets <code>min</code>or <code>max</code> to <code>0</code>, that property turns to undefined!<br>
Why is this and how can I store a simple 0?</p>

<p>Here a jsFiddle: <a href="http://jsfiddle.net/KDXa6/2/" rel="nofollow">http://jsfiddle.net/KDXa6/2/</a></p>
