BUG in GameUtil.SoundManager

There are a couple of bugs in GameUtil.SoundManager. This is only a problem if you need to remove sound groups. Here's the gist of the problem (not too hard to fix).

1) in public virtual void Reset()

...
// unregister all sound groups
for (int i = 0; i < _soundGroups.Count; i++)
UnregisterSoundGroup(_soundGroups[i] as SoundGroup);

This doesn't work because _soundGroups is a HashTable so _soundGroups[i] as SoundGroup is always null.
If you fix this say by

foreach (DictionaryEntry myDE in _soundGroups)
UnregisterSoundGroup(myDE.Value as SoundGroup);

The next problem shows up

2) in public virtual void UnregisterSoundGroup(SoundGroup group)

...
_soundGroups.Remove(group);

This doesn't work because Remove expects a key, not a value.
If you fix this by passing in the key, then the Remove modifies the HashTable which will screw up the foreach in (1) above.

There are a few different ways to fix this depending on your preferences ...