Compare the contents of this CXlRef with another
int Compare( const CXlRef& other ) const;
An initialised CXlRef.
Returns 1 if the value in this object is greater than that in other, -1 if other is less and 0 if the two are equal.
This function acts like strcmp() and similar 'C' library functions.
Note that CXlRefs are sorted by rows first and then by columns.