message: New chart option: valAxisCrossesAt
diff: @@ -3609,6 +3609,7 @@ var PptxGenJS = function(){
  function makeCatAxis(opts, axisId, valAxisId) {
  var strXml = '';
  + var crosses = opts.valAxisCrossesAt ? opts.valAxisCrossesAt : 'autoZero';
  // Build cat axis tag
  // NOTE: Scatter and Bubble chart need two Val axises as they display numbers on x axis
  @@ -3675,7 +3676,7 @@ var PptxGenJS = function(){
  strXml += ' </a:p>';
  strXml += ' </c:txPr>';
  strXml += ' <c:crossAx val="'+ valAxisId +'"/>';
  - strXml += ' <c:crosses val="autoZero"/>';
  + strXml += ' <c:' + ((typeof crosses == "number") ? 'crossesAt' : 'crosses') + ' val="' + crosses + '"/>';
  strXml += ' <c:auto val="1"/>';
  strXml += ' <c:lblAlgn val="ctr"/>';
  strXml += ' <c:noMultiLvlLbl val="1"/>';
  