Add max keyword argument to difference/derivative functions.

[adamperlin]

From ifql created by nathanielc : influxdata/ifql#223

https://github.com/influxdata/influxdb/issues/5954

The max helps account for integer wrap.

[jsternberg]

The function signature has to be discussed before working on this so if you are a community member planning to work on this, please consult us about API design before beginning your work. Thanks.

[davidby-influx]

@timhallinflux - this resurfaced in another issue in which I will tag you. I have provided a work-around in that issue, but this is obviously a better (but more expensive) solution for Flux to implement.