Implemented love.system.vibrate on iOS. Unfortunately due to API limitations the duration argument is ignored, and it always vibrates for roughly 0.5 seconds.

src/modules/system/System.cpp

@@ -146,6 +146,8 @@ void System::vibrate(double seconds) const
 {
 #ifdef LOVE_ANDROID
 	love::android::vibrate(seconds);
+#elif defined(LOVE_IOS)
+	love::ios::vibrate();
 #else
 	LOVE_UNUSED(seconds);
 #endif