title: Magento getStoreConfig : get label
body: <p>first of all i have a model class like this : </p>
  
  <pre><code>class namespace_mymodule_Model_myclass
      {
          public function toOptionArray()
          {
                return array(
                             array('value'=&gt;'My value',
                                   'label'=&gt;Mage::helper('mymodule')-&gt;__('My label name')
                                  )
                            );         
          }
      }
  </code></pre>
  
  <p>So i get the value from my configuration like this : </p>
  
  <pre><code>Mage::getStoreConfig('section/group/dropdown'); = 'My value'
  </code></pre>
  
  <p>how can i get the label ? </p>
  
  <pre><code>????????????????????; = 'My label name'
  </code></pre>