FPSpreadsheet: Adds support to 16 possible background colors to biff 8

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@1648 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/examples/excel8demo/excel8write_format.pas

@@ -108,6 +108,7 @@ begin
   MyWorksheet.WriteUTF8Text(5, 9, '[N,W,E,S]');// J6
   MyCell := MyWorksheet.GetCell(5, 9);
   MyCell^.Border := [cbNorth, cbWest, cbEast, cbSouth];
+  MyCell^.BackgroundColor := scGreen;
   MyCell^.UsedFormattingFields := [uffBorder, uffBold, uffBackgroundColor];
 
   // Save the spreadsheet to a file