Added audio_utils.h/.c and refactored calls to mmEffectEx to use wrapper play_sfx() instead

source/audio_utils.c

@@ -0,0 +1,8 @@
+#include "audio_utils.h"
+#include <maxmod.h>
+
+void play_sfx(mm_word id, mm_word rate)
+{
+    mm_sound_effect sfx = { {id}, rate, 0, SFX_DEFAULT_VOLUME, SFX_DEFAULT_PAN, };
+    mmEffectEx(&sfx);
+}