ENH: BusinessHour to support multiple opening and closing times per day

[jzwinck]

BusinessHour supports arbitrary start and end times. But some businesses open and close more than once per day. Some examples:

• Restaurants, who might want to analyze foot traffic or revenue, but excluding times they don't open.
• Stock markets, several of which have a lunch break.
• Mexico, where standard business hours are 07:00-14:00 and 16:00-18:00.

Many use cases could be satisfied by just two opens and two closes per day, but it might be just as well to support any amount.

[jreback]

can you give a pseudo code example of how this would work? (constructor, usage, etc), compared to using just one o/c

[jzwinck]

It could be done using arrays or lists for start and end in the BusinessHour and CustomBusinessHour constructors. For example:

mexico_hour = BusinessHour(start=['07:00', '16:00'], end=['14:00', '18:00'])

Or it could be done using a single 2D set of start and end times:

mexico_hour = BusinessHour(open=[['07:00', '14:00'], ['16:00', '18:00']])

Personally I'd be happy with either. Once constructed, usage should be exactly the same. For example if I add one mexico_hour to 2017-02-23 13:30 I would expect to get 2017-02-23 16:30, and if I add seven hours I would expect to get 2017-02-24 11:30.

[jreback]

ok doesn't seem unreasonable. I had a brief look at the current impl. It does seem that this could be done in a back-compat way, though might be some semantic confusions, e.g. since open can now occur multiple times per day.

so would take a community PR to do this!

@sinhrks