we can add properties to tr, th or td

by pass an object as a row or cell data, we can add properties to tr, th or td.
we use the key '_data' to store the real data, other keys and values will be set as tr, th or td's properties.
eg.[
  {id:'header',_data:['TH1','TH2']},
  ['TD1',{class:'td2',_data:['TD2']}]
]
will set the first row's id to 'header' and TD2's class to 'td2'.