Improved year fraction calculation

The year fraction is now calculated from seconds in the current date and is more granular. This means that the year fraction is correctly updated when it changes, not simply every day. Thus, on 1 January 2014 the date starts with 0 000 014.M3 instead of the rounded up 0 003 014.M3 and updates to 0 001.014.M3 within the first day.