Manipulate date and time: Add and subtract a period to a date

This is a siple class that can be used to perform arithmetic operations with dates.

It can add or subtract a period in years, months, days, hours, minutes and seconds to a given date or a time.

The code and comments are in Spanish.

In Spanish:

Esta clase te permite aumentar y disminuir la fecha y hora, y obtener una cadena con la fecha segun un formato ingresado (Use como base cdate).