Avoid PHP Warning:  json_encode(): Invalid UTF-8 sequence in argument
Fix set private/public button success messages in plugin settings
Repair .js timezone detection

Upgrading query to current versions broke timezone detection due to slash being present in timezone signifiers. Now just using the city/region name to select correct values. Assumes there's only one city of each name in this subset list, but that should be fine. Also upgraded the timezone js library by 3 years.