Add setters for highest row and column.

Classes/PHPExcel/Worksheet.php

@@ -1023,6 +1023,16 @@ public function getHighestColumn($row = null)
         return $this->getHighestDataColumn($row);
     }
 
+    /**
+     * Set highest worksheet column
+     *
+     * @param   string     $column
+     */
+    public function setHighestColumn($column)
+    {
+      $this->cachedHighestColumn = $column;
+    }
+
     /**
      * Get highest worksheet column that contains data
      *
@@ -1050,6 +1060,16 @@ public function getHighestRow($column = null)
         return $this->getHighestDataRow($column);
     }
 
+    /**
+     * Set highest worksheet row
+     *
+     * @param   string     $row
+     */
+    public function setHighestRow($row)
+    {
+       $this->cachedHighestRow = $row;
+    }
+
     /**
      * Get highest worksheet row that contains data
      *