Deprecated operators for DateTime private members

[Peter]

**timothee** , your solution (and the alternative ways mentioned in the PR 
discussion) could be a solution. But the situation is more delicate here. These 
fields _were_ public, they passed to private in the patch I've mentioned. And 
the operators (deprecated!) were introduced to overcome the potential access 
problems. So, probably, there is some logic, but I don't understand it. That's 
why I asked this question.