void Worksheet::mergeCells (
This is an Excel97/2000 method. It is required to perform more complicated merging than the normal setAlign('merge'). It merges the area given by its arguments.
integer $first_row - First row of the area to merge
integer $first_col - First column of the area to merge
integer $last_row - Last row of the area to merge
integer $last_col - Last column of the area to merge
This function can not be called statically.