Modify setEndDateYear and setStartDateYear to mark hasEndDate and hasStartDate to be true only when the input is not null.
Add hasStartDate, hasStartTime, hasEndDate, hasEndTime attributes to Task class. Add accessors and mutators for these attributes. Update toString method in Task class to print the modified attributes over the last few commits.
Merge branch 'master' of https://github.com/cs2103aug2014-T13-2J/main