add data-numeric attribute to html table cells

[kbvernon]

Prework

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• Search for duplicates among the existing issues (both open and closed).

Proposal

Maybe consider adding a data-numeric attribute to table cells if is.numeric(x):

<td data-numeric></td>

so we could then target those columns in CSS with specific formatting:

td[data-numeric] {
  text-align: right;
}

This would be particularly useful in situations where people want the bare HTML table with no CSS, as requested in #816.