Enhance Pavlovia data filename: Disambiguate recorded time by appending, e.g. "UTC+6"

Pavlovia saves data in CSV files. The date is saved in the filename. The date is in the local time of the participant’s computer. Many of us deploy experiments across many time zones, so the recorded time is currently ambiguous. Please enhance Pavlovia by adding “UTC+?”, e.g. “UTC+6” for New York City, to the recorded time in the data file name. The javascript call getTimezoneOffset provides the UTC offset in minutes. Divide by 60 to get hours.