title: convert xls to csv without any data changes
body: <p>I have xls file, in him is very  unicode data, also data like this <code>0004</code> and etc.</p>
  
  <p>I need convert this file to csv format, but if simple <code>save as csv</code> from ms excel, data are changed, unicode symbols converted to - <code>???</code>,   data like this <code>0004</code>, converted to <code>4</code></p>
  
  <p>There are possible to convert xls to csv   without any data changes ?</p>