Deprecated operators for DateTime private members

[Hlaaftana]

Sorry, I didn't catch this on your last thread, I'm guessing what you're 
expected to do is call `initDateTime` with all the fields, though I don't think 
this is possible to do given you inherit from DateTime. Maybe DateTime should 
be changed to be non-inheritable. What you probably have to do is have a 
`datetime: DateTime` field on your object then act on that field.