Update AndroidX Core to version 1.7.0
Update AndroidX Activity to version 1.4.0
Update Androidx Fragment to version 1.3.6
Update Androidx Lifecycle to version 2.4.0
Add AppLanguageManager that notifies listeners when the app language has been changed. K9Activity uses this mechanism to restart() on language changes. The Application object will update its configuration.
Instead of using the deprecated Resources.updateConfiguration() we now use LocaleContextWrapper (in combination with AppCompat) to override the locale in the configuration.