Add support for preserving and exporting the macros in a macro-enabled workbook.

Macros are pieces of code written in Visual Basic for Applications (VBA) which are used to automate repetitive tasks in excel. The macros are part of the excel file. When a file contains a macro its extension becomes xlsm.

SpreadProcessing should be able to import and export xlsm files and edit the macros in them.

When a TrueType font is defined, the mapping of character codes to glyph indices depends on the built-in cmap table mappings defined in the font and the Encoding property defined in the PDF dictionary.

However, the current implementation maps all characters with cmap tables for Microsoft Symbolic and Macintosh Roman, which causes incorrect mapping results, e.g. space characters are mapped to an Ê glyph.

The issue is also described in the following public item: TryGetCharCode for OpenTypeFont uses wrong cmap and returns wrong charcode.

Workaround: Change the font  of the TextBoxField's widget appearance:
foreach (var widget in field.Widgets)
{
    widget.TextProperties.Font = FontsRepository.Helvetica;
}

For example when some PDF file has uncompressed contents we may import it and apply better compression to the stream objects. Ensure that all the content inside the document is compressed.

To reproduce: 

- Add the following formula to a cell: "=A1=FALSE"

Actual: the result is always false

Expected: the result should be true when the cell is empty

Workaround: Use the ISBLANK function.

This exception corrupts the whole document import. Instead, we should provide Exception handling mechanism which allows the user to import the rest of the content.

If a worksheet spans more than one page, you can print row and column headings or labels (also called print titles) on every page to ensure that the data is properly labeled.

Handle the case where the formula starts with "=+". Detailed information: https://professor-excel.com/equal-plus-excel-formulas/

Workaround: replace the "=+" with "="

CellRange usedCellRange = workbook.Worksheets[0].UsedCellRange;

for (int rowIndex = usedCellRange.FromIndex.RowIndex; rowIndex <= usedCellRange.ToIndex.RowIndex; rowIndex++)
{
    for (int columnIndex = usedCellRange.FromIndex.ColumnIndex; columnIndex <= usedCellRange.ToIndex.ColumnIndex; columnIndex++)
    {
        CellSelection cell = workbook.Worksheets[0].Cells[rowIndex, columnIndex];
       

        FormulaCellValue formulaCellValue =cell.GetValue().Value as FormulaCellValue;
        if (formulaCellValue == null)
        {
            continue;
        }
        CellValueFormat format = cell.GetFormat().Value;
        string resultValueAsString = formulaCellValue.GetValueAsString(format);
        Console.WriteLine(resultValueAsString);
        if (resultValueAsString.StartsWith("=+"))
        {
            resultValueAsString = resultValueAsString.Remove(1, 1);
            cell.SetValue(resultValueAsString);
        }
    }
}
radSpreadsheet.Workbook = workbook;