title: Adding 7 days to date in xdsoft datetimepicker
body: <p>I'm using <a href="http://xdsoft.net/jqplugins/datetimepicker/" rel="nofollow">XD Soft DateTimePicker</a> for displaying datepicker.</p>
  
  <p>I have two text-boxes "txtFromDate" and "txtToDate"</p>
  
  <hr>
  
  <p><strong>What I need?</strong></p>
  
  <p>When I select a date in "txtFromDate" then the "txtToDate" can only select the next 7 days. ie. max date in "txtToDate" will be +7 days of selected days in "txtFromDate"</p>
  
  <hr>
  
  <p><strong>What I done so far?</strong></p>
  
  <p>I have this code</p>
  
  <pre><code>jQuery(function () {
          jQuery('#txtFromDate').datetimepicker({
              format: 'd/m/Y',
              onShow: function (ct) {
                  this.setOptions({
                      maxDate: jQuery('#txtToDate').val() ? jQuery('#txtToDate').val() : false,
                      formatDate: 'd/m/Y'
                  })
              },
              timepicker: false,
          });
          jQuery('#txtToDate').datetimepicker({
              format: 'd/m/Y',
              onShow: function (ct) {
                  this.setOptions({
                      minDate: jQuery('#txtFromDate').val() ? jQuery('#txtFromDate').val() : false,
                      maxDate: ???? //Need to set +7days date of txtFromDate here,
                      formatDate: 'd/m/Y'
                  })
              },
              timepicker: false,
          });
  
      });
  </code></pre>
  
  <p>Here I want to add 7 days to the maxDate of txtToDate.</p>
  
  <p>How to add days to the date assigned to maxDate of txtToDate?</p>