Use UTF-8 for JSON

[Huulivoide]

The year is 2019, those refusing to use anything but ASCII should be the one to suffer, not the 99% of people whose systems are able to handle UTF-8. So instead of escaping all non ASCII characters on the data, they really should be just in plain, pretty, readable UTF-8.

One might also consider pretty printing the json data.

[umpirsky]

Note to myself, this can be achieved with JSON_UNESCAPED_UNICODE.