Changes:
ZCL_EXCEL_WORKSHEET: New attributes to hold row-outline information
ZCL_EXCEL_WORKSHEET_ROWDIMENSI: Look at those row-outline information. Modified methods that refer to outlining
ZCL_EXCEL_WRITER_2007: Respect new outlining informatino by using the modified methods from rowdimensi, Also corrected an error that occurs if we have leading or trailing empty rows but information stored in rowdimensions
ZDEMO_EXCEL12: Modified Demoreport 12 to demonstrate new outlining method