code: function changeId(content, filePath, name, idSep) {
      if (idSep === void 0) { idSep = '_'; }
      var idReg = /svgicon(\w+)/g;
      content = content.replace(idReg, function (match, elId) {
          return "svgicon" + idSep + filePath.replace(/[\\\/]/g, idSep) + name + idSep + elId;
      });
      return content;
  }
docs: replace element id, make sure ID is unique. fix #16