title: dataTables search messed up by input from another form
body: <p>hello i have a form like this </p>
  
  <pre><code>&lt;form id="ricerca" enctype="application/x-www-form-urlencoded" method="post" action=""&gt;&lt;table class="inserisci_modifica"&gt;
  &lt;tr class="visualizza_dati"&gt;
  
  &lt;td class="nome_campo"&gt;&lt;label for="ragsoc_denominazione"&gt;Ragione sociale o denominazione&lt;/label&gt;&lt;/td&gt;
  &lt;td class="valore_campo"&gt;
  &lt;input type="text" name="ragsoc_denominazione" id="ragsoc_denominazione" value="" tabindex="1" /&gt;&lt;/td&gt;
  &lt;td class="nome_campo"&gt;&lt;label for="piva"&gt;Partita IVA&lt;/label&gt;&lt;/td&gt;
  &lt;td class="valore_campo"&gt;
  &lt;input type="text" name="piva" id="piva" value="" tabindex="9" /&gt;&lt;/td&gt;&lt;/tr&gt;
  </code></pre>
  
  <p>then i have an html table to which i apply dataTables</p>
  
  <p>and then i have this code</p>
  
  <pre><code>$("#ricerca").submit(function(event) {
      event.preventDefault();
      oTable.fnClearTable();//Empty the entire table of current row information.
      oTable.fnDraw();
  });
  </code></pre>
  
  <p>the problem is when i type something in my form, it's as if it gets auto submited as dataTables's search field, and then i can see the same text in dataTables search field, i can't understand why</p>