Allow choosing language in-app

app/src/main/java/de/kuschku/quasseldroid/Quasseldroid.kt

...va/de/kuschku/quasseldroid/settings/AppearanceSettings.kt

...rc/main/java/de/kuschku/quasseldroid/settings/Settings.kt

.../kuschku/quasseldroid/ui/chat/input/AutoCompleteHelper.kt

...ldroid/ui/clientsettings/client/ClientSettingsFragment.kt

...in/java/de/kuschku/quasseldroid/ui/setup/SetupActivity.kt

...main/java/de/kuschku/quasseldroid/util/ui/LocaleHelper.kt

...in/java/de/kuschku/quasseldroid/util/ui/ThemedActivity.kt

app/src/main/res/values/strings_preferences.xml

app/src/main/res/xml/preferences.xml

...main/java/de/kuschku/libquassel/util/helpers/AnyHelper.kt

...va/de/kuschku/libquassel/util/helpers/ObservableHelper.kt

...java/de/kuschku/quasseldroid/viewmodel/EditorViewModel.kt

...ava/de/kuschku/quasseldroid/viewmodel/QuasselViewModel.kt