This reverts most of commit ede5c9548e.
The one change not reverted is ClockWidget.h, so that the taskbar clock
can continue to notice time zone changes.
In most applications, we invoke tzset once at startup for now. Most of
these are short lived and don't need to know about time zone changes.
The exception is the ClockWidget in the taskbar. Here, we invoke tzset
each time we update the system time. This way, any time zone changes can
take effect immediately.
Also add slightly richer parse errors now that we can include a string
literal with returned errors.
This will allow us to use TRY() when working with JSON data.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
