Timezone optionality

[pinguicula]

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)