Fix scrolling wrap-around in settings menu (#249)

## Summary

Fixes a bug in the settings menu, where previously wrap-around only
worked when scrolling upwards. Now, scrolling downwards on the last list
element wraps around to the top as expected.

Resolves #236.

src/activities/settings/SettingsActivity.cpp

@@ -114,13 +114,11 @@ void SettingsActivity::loop() {
     updateRequired = true;
   } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
              mappedInput.wasPressed(MappedInputManager::Button::Right)) {
-    // Move selection down
-    if (selectedSettingIndex < settingsCount - 1) {
-      selectedSettingIndex++;
+    // Move selection down (with wrap around)
+    selectedSettingIndex = (selectedSettingIndex < settingsCount - 1) ? (selectedSettingIndex + 1) : 0;
     updateRequired = true;
   }
 }
-}
 
 void SettingsActivity::toggleCurrentSetting() {
   // Validate index