fpspreadsheet: Write text format to ods, xlsx, biff8 and biff5

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@4539 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/fpsopendocument.pas

@@ -906,6 +906,9 @@ begin
             ' ': Result := Result + '<number:text><![CDATA[ ]]></number:text>';
             else Result := Result + '<number:text>' + Elements[el].TextValue + '</number:text>';
           end;
+
+        nftTextFormat:
+          Result := Result + '<number:text-content />';
       end;
 
       inc(el);

components/fpspreadsheet/xlscommon.pas

@@ -846,7 +846,7 @@ begin
   AList.Add('[h]:nn:ss');   // 46
   AList.Add('nn:ss.z');     // 47
   AList.Add('##0.0E+00');   // 48
-  AList.Add('');            // 49: @ ("Text") not supported
+  AList.Add('@');           // 49 "Text" format
   for i:=50 to ALastIndex do AList.Add('');  // not supported/used
 end;