message: updated `displayBlanksAs` setup
diff: @@ -529,6 +529,7 @@ var PptxGenJS = function(){
  // lineDataSymbol: http://www.datypic.com/sc/ooxml/a-val-32.html
  // Spec has [plus,star,x] however neither PPT2013 nor PPT-Online support them
  if ( ['circle','dash','diamond','dot','none','square','triangle'].indexOf(options.lineDataSymbol || '') < 0 ) options.lineDataSymbol = 'circle';
  + if ( ['gap','span'].indexOf(options.displayBlanksAs || '') < 0 ) options.displayBlanksAs = 'gap';
  options.lineDataSymbolSize = ( options.lineDataSymbolSize && !isNaN(options.lineDataSymbolSize ) ? options.lineDataSymbolSize : 6 );
  options.lineDataSymbolLineSize = ( options.lineDataSymbolLineSize && !isNaN(options.lineDataSymbolLineSize ) ? options.lineDataSymbolLineSize * ONEPT : 0.75 * ONEPT );
  // `layout` allows the override of PPT defaults to maximize space
  @@ -2581,7 +2582,7 @@ var PptxGenJS = function(){
  }
  strXml += ' <c:plotVisOnly val="1"/>';
  - strXml += ' <c:dispBlanksAs val="' + (rel.opts.displayBlankAs ? rel.opts.displayBlankAs : 'gap') + '"/>';
  + strXml += ' <c:dispBlanksAs val="'+ options.displayBlanksAs +'"/>';
  if ( rel.opts.type.name === 'scatter' ) strXml += '<c:showDLblsOverMax val="1"/>';
  strXml += '</c:chart>';
  @@ -5051,7 +5052,7 @@ if ( NODEJS ) {
  var JSZip = null;
  var sizeOf = null;
  - // A: jQuery depdendency
  + // A: jQuery dependency
  try {
  var jsdom = require("jsdom");
  var dom = new jsdom.JSDOM("<!DOCTYPE html>");
  