* Update to xlsx.js 0.7.10
* Handle "bare" .xlsx <r> and <c> tags.

  An example of such an out-of-spec sheet XML snippet (provided by @EarlJS):

  <sheetData>
    <row s="1199" customFormat="1">
      <c s="1259" t="s">
        <v>1637</v>
      </c>
    </row>
  </sheetData>
* Update manifest