In this PR we introduced 3 new timezones to UX - IST, KST and JST
cb2569303f
However, the same has to be done in PrettyText so cooked posts respect those timezones.
Essentially,
Saturday at 2:50 PM -> Saturday at 4:38 PM becomes
Saturday at 2:50 PM -> 4:38 PM (Singapore)
Also, the displayed dates are shortened when the standalone date
is within two days. So despite the 'from' and 'to' date being the
same day, it may show 'Saturday' for 'from', and the specific date
for the 'to'. This corrects the behaviour.
(so if the current date and time is Thursday 5PM, the 'from' date
below is within 2 days, but the 'to' date is not)
Saturday at 2:50 PM -> 8 October 2022 at 9:38 PM becomes
Saturday at 2:50 PM -> 9:38 PM
New range tag for local dates with syntax like:
```
[date-range from=2022-01-06T13:00 to=2022-01-08 timezone=Australia/Sydney]
```
Previously, 2 dates in one line were considered as range. It was hard to decide if 2 dates are range when they were in separate lines or have some content between them.
New explicit tag should clearly distinguish between single date and range.
Common code from `addLocalDate` is extracted to `addSingleLocalDate`.
Both `addLocalDate` and new `addLocalRange` are using `addSingleLocalDate`.
Also, `defaultDateConfig` was extracted to have one place for all possible parameters.
