[Cog Decoder Multi] Add dealloc function to close

Add dealloc function to close the file container, in case the caller
neglected to do so on its own.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/CogPluginMulti.m

@@ -112,6 +112,10 @@ static void *kCogDecoderMultiContext = &kCogDecoderMultiContext;
 	}
 }
 
+- (void)dealloc {
+	[self close];
+}
+
 - (void)registerObservers {
 	if(!observersAdded) {
 		[theDecoder addObserver:self