public String formatCellValue(Cell cell, FormulaEvaluator evaluator) {
        return formatCellValue(cell, evaluator, null);
    }
<p>
Returns the formatted value of a cell as a <tt>String</tt> regardless of the cell type. If the Excel number
format pattern cannot be parsed then the cell value will be formatted using a default format.
</p>
<p>
When passed a null or blank cell, this method will return an empty String (""). Formula cells will be evaluated
using the given {@link FormulaEvaluator} if the evaluator is non-null. If the evaluator is null, then the formula
String will be returned. The caller is responsible for setting the currentRow on the evaluator
</p>

@param cell      The cell (can be null)
@param evaluator The FormulaEvaluator (can be null)
@return a string value of the cell
fastexcel-test/src/test/java/cn/idev/excel/test/temp/dataformat/DataFormatter1.java