fix(ui): hacky fix for updating colors on show question marks setting change

This only applies if the grey completed setting is enabled.
This is to avoid restarting the app to see the resulting color change,
when changing the show question marks setting.

It'll be good to call `finish()` on the settings activity,
to avoid stacking activities every time the setting is changed.

uhabits-android/src/main/java/org/isoron/uhabits/activities/habits/list/ListHabitsActivity.kt

@@ -75,8 +75,12 @@ class ListHabitsActivity : AppCompatActivity(), Preferences.Listener {
     private lateinit var menu: ListHabitsMenu
 
     override fun onQuestionMarksChanged() {
-        invalidateOptionsMenu()
+        if (prefs.greyCompleted) {
-        menu.behavior.onPreferencesChanged()
+            restartWithFade(this::class.java)
+        } else {
+            invalidateOptionsMenu()
+            menu.behavior.onPreferencesChanged()
+        }
     }
 
     override fun onCreate(savedInstanceState: Bundle?) {