set_by_second
Description:
Sets the by_second array from Recurrence at the given index.
The array size is I_CAL_BY_SECOND_SIZE.
Parameters:
| this | The Recurrence | 
| index | The index in by_second of Recurrence, less than I_CAL_BY_SECOND_SIZE | 
| value | The value to be set into by_second of Recurrence |