Enable translation scripting for date groups

Enable translation scripting for date groups

This allows to work around limitations in Qt's date formatting.

Examples:

* Uppercasing the first character in a string because it's a title:
  Day of the week and month names returned by QDateTime::toString
  are usually lowercase.
* Correcting the noun case of a month name from "of [month]" to
  "in [month]" in Finnish: "of [month]" is correct when talking
  about a specific day, but wrong when talking about a specific month.

REVIEW: 123278