It fixes several bugs:
- Fixed bug #45554 (Inconsistent behavior of the u format char).
- Fixed bug #48225 (DateTime parser doesn't set microseconds for "now").
- Fixed bug #52514 (microseconds are missing in DateTime class).
- Fixed bug #52519 (microseconds in DateInterval are missing).
- Fixed bug #68506 (General DateTime improvments needed for microseconds to become useful).
- Fixed bug #73109 (timelib_meridian doesn't parse dots correctly).
- Fixed bug #73247 (DateTime constructor does not initialise microseconds property).
It also updates timelib to 2016.04, and updates a data mapping file, which
causes changes to the volatile abbreviations tests.