Fix DST issue (closes #972, closes #992)

[kossnocorp]

Rework approach to DST handling to make it more bulletproof.

To do:

• Fix the problem
• Check extreme cases such as https://www.huffingtonpost.com/2011/12/28/samoa-time-zone-change_n_1172922.html?guccounter=1

[kronthto]

I think taking the next day into consideration causes weird behaviour in some cases. See:

// import dateformat from 'date-fns/format'

> dateformat('2019-10-26T22:40:00')
"2019-10-26T23:40:00.000+02:00"

(format calling parse)
It makes 23:40 out of 22:40.

date-fns version: 1.30.1 - this change was backported there.

This is with a Europe/Berlin Browser/system timezone, we have DST change at 2019-10-27 03:00 (the day after that date).

Sorry if this was already reported/fixed elsewhere, or I'm wrong / this is intended. Tbh. I didn't put too much effort into tracking it down further but it lead me here and I wanted to report it.

Yep I see there is already #1500 so ignore this.