TZ and DST changes fix

[andyrozman]

When we travel towards east (time is added) there is no problem with Medtronic history, but when we go back to west and time is subtracted, then the problems can ensue...

To prevent this we need to modify history reading.

• if time has changed by substraction, then we need to read history just until time change (history goes from oldest to newest in pump), so we need to ignore all entries happened before time change...

[xJoe]

Would workaround for Dana RS (if someone can't or does not want to delete Dana history) also work for Medtronic? https://androidaps.readthedocs.io/en/latest/EN/Usage/Timezone-traveling.html#option-1-keep-home-time-and-timeshift-profile