Add support for fading in to sound groups.

research/ma_engine.c

@@ -37,6 +37,7 @@ int main(int argc, char** argv)
 
     //ma_engine_sound_group_set_pan(&engine, NULL, -1);
     ma_engine_sound_group_set_pitch(&engine, NULL, 1.0f);
+    ma_engine_sound_group_set_fade_in(&engine, NULL, 4000);
     
     /*ma_engine_sound_set_volume(&engine, &sound, 0.25f);*/
     //ma_engine_sound_set_pitch(&engine, &sound, 2.0f);
@@ -58,7 +59,7 @@ int main(int argc, char** argv)
     ma_engine_play_sound(&engine, argv[3], NULL);*/
 #endif
 
-#if 1
+#if 0
     float pitch     = 1;
     float pitchStep = 0.01f;
     float pitchMin  = 0.125f;