Replace UCT Offsets with IANA Timezones

[ghplw]

Currently showing the "local" time uses UTC offsets which are in 1 hour blocks. This puts the time out by half an hour in many places and doesn't follow local DST rules.

Using the IANA Timezone database (https://www.iana.org/time-zones) would mean that we can have both the correct time and won't have to manually change the offset twice a year.

[max-arnold]

Including the whole TZ database is an overkill - there are too many entries to select from. Also the receiver doesn't keep the time when switched off, so timekeeping is not a primary function.

With that said, I added a complete list of UTC offsets with 15 minute granularity #287

[max-arnold]

Here is the list, please let me know if some offset is missing

ats-mini/ats-mini/Menu.cpp

Line 216 in 9793308

const UTCOffset utcOffsets[] =

[ghplw]

Looks like you've got them all. Thankyou :)