Timezone optionality

The local system is set to UTC (and I agree that all records should be saved in UTC). But it would be good to be able to display the times in a selected local zone (initial implementation could be a time-offset that is manually adjusted to not have to deal with the tz-implementation)

In summary, the suggestion is:
1. Add option to have an hour offset in displayed time
2. Add functionality to handle timezones and display based on zone rather than simple hourly offset.
3. Add support to store the offset (replace Z with +nn:00)

Start by mapping the existing time display and storage entry points, since the issue names no files or tests. Define the scope for a manual display offset, timezone-based display, and storing offsets, then verify that records remain saved in UTC while displayed times follow the selected setting.

Written by the indexing model from the issue text.