Samanzamani PersianDate Versions Save

Fix add/sub reported bug (Reported By @Alireza-Jamali).[https://github.com/samanzamani/PersianDate/issues/81] Add new adds methods: addWeeks,addDays,addMonths,addYears,addHours,addMinutes,.... Add new subs methods: subsWeeks,subsDays,subsMonths,subsYears,subsHours,subsMinutes,.... Increase test coverage.