Suggested addition to rollup callendar intervals

[local-minimum]

Pond.js has some fantastic ease of use TimeSeries roll-up functions, but it does have support for iso standard weeks (Monday - Sunday), nor it seems the US/Canada non-standard Sunday-Saturday is supported.

From what I've gleaned the most proximate possibility is

const ts = new TimeSeries(data);
const weekly = ts.fixedWindowRollup({ windowSize: '7d', aggregation: { in: { in: sum() } } });

But as the unix epoch wasn't on a Monday, nor Sunday for that matter, this splits the data in the middle of the week.

Suggested interface

Using fixedWindowRollup for Monday - Sunday:

const ts = new TimeSeries(data);
const weekly = ts.fixedWindowRollup({ windowSize: 'weekly', aggregation: { in: { in: sum() } } });

Using fixedWindowRollup for Sunday - Saturday, if such support should be included:

const ts = new TimeSeries(data);
const weekly = ts.fixedWindowRollup({ windowSize: 'weekly-1', aggregation: { in: { in: sum() } } });

If non-standard Sunday - Saturday needs to be included, then probably all offsets should be as there's a variety of non-standard first days of the week around the world.

If a weeklyRollup method should be included, it's a bit unclear what the interface ought to be, but perhaps only a support of iso-weeks with TimeSeries.weeklyRollup(options)