Support IOF v3.0 XML format files

Still need to check that the rest of the system can handle
cumulative/split times in fractional seconds.
Use more realistic test data

IOF XML v3 uses times specified as seconds rather than MM:SS.
Support fractional times

Fractional times with a resolution of 1/100 of a second are now visible
in the UI.
Use consistent time formatting on results table

If the event uses fractional seconds, then some cumulative and split
times may happen to be a whole number of seconds.  Such times should
still be formatted to the same precision.

Fixes #18.