newer blog time and date format

see title
The new date format is the year followed by the day of year. Unfortunately WordPress’ day of year is zero-based (so Jan 1 is day 0) so I’ve added “+1” to the end to fix that. Hopefully adding 1 won’t cause too much of an inconvenience.
The time format is now the number of milliseconds since the beginning of 1970/0+1, but WordPress always rounds to the nearest seconds so far.