system theme (automatic switch between light/dark theme)

app/src/main/java/de/beowulf/wetter/GlobalFunctions.kt

...ain/java/de/beowulf/wetter/activities/SettingsActivity.kt

app/src/main/res/values-b+sr+Latn/strings.xml

app/src/main/res/values-bg/strings.xml

app/src/main/res/values-bs/strings.xml

app/src/main/res/values-cs/strings.xml

app/src/main/res/values-de/strings.xml

app/src/main/res/values-el/strings.xml

app/src/main/res/values-eo/strings.xml

app/src/main/res/values-es/strings.xml

app/src/main/res/values-fi/strings.xml

app/src/main/res/values-fr/strings.xml

app/src/main/res/values-hy/strings.xml

app/src/main/res/values-it/strings.xml

app/src/main/res/values-ka-rGE/strings.xml

app/src/main/res/values-mk/strings.xml

app/src/main/res/values-nl/strings.xml

app/src/main/res/values-pl/strings.xml

app/src/main/res/values-pt-rBR/strings.xml

app/src/main/res/values-ru/strings.xml