feat: Support all current timezones for GPS (#3406)

* Support all current timezones.

* Fix function name and calculation for timezone offset.

* Allow setting any time offset value from -12 to +14 in 15 minutes increments.

* Alternate timezone editor in Companion (from elecpower).

* Fix compiler warning.

* chore: Add the T20

companion/src/generaledit/generalsetup.cpp

@@ -150,7 +150,8 @@ ui(new Ui::GeneralSetup)
   }
 
   ui->gpsFormatCB->setCurrentIndex(generalSettings.gpsFormat);
-  ui->timezoneSB->setValue(generalSettings.timezone);
+
+  ui->timezoneLE->setTime((generalSettings.timezone * 3600) + (generalSettings.timezoneMinutes/*quarter hours*/ * 15 * 60));
 
   if (IS_HORUS_OR_TARANIS(firmware->getBoard())) {
     ui->adjustRTC->setChecked(generalSettings.adjustRTC);
@@ -328,6 +329,16 @@ GeneralSetupPanel::~GeneralSetupPanel()
   delete ui;
 }
 
+void GeneralSetupPanel::on_timezoneLE_textEdited(const QString &text)
+{
+  if (!lock) {
+    int secs = ui->timezoneLE->timeInSeconds();
+    generalSettings.timezone = secs / 3600;
+    generalSettings.timezoneMinutes = (secs % 3600) / (15 * 60); // timezoneMinutes in quarter hours
+    emit modified();
+  }
+}
+
 void GeneralSetupPanel::populateBacklightCB()
 {
   QComboBox * b = ui->backlightswCB;
@@ -693,12 +704,6 @@ void GeneralSetupPanel::on_switchesDelay_valueChanged(int)
   emit modified();
 }
 
-void GeneralSetupPanel::on_timezoneSB_editingFinished()
-{
-  generalSettings.timezone = ui->timezoneSB->value();
-  emit modified();
-}
-
 void GeneralSetupPanel::on_adjustRTC_stateChanged(int)
 {
   generalSettings.adjustRTC = ui->adjustRTC->isChecked();