Now you can say d3.time.seconds(start, stop, step), which will return every
step'th second after start (inclusive) and before stop (exclusive). In addition,
you can now pass a range method to the time scale's ticks method, which makes it
easier to generate ticks. For example, x.ticks(d3.time.seconds, 15) will return
15-second ticks, rather than using the automatic default.
Mike Bostock