preserve aud codec state across blocks, so the gain isnt completely bogus

OpenRA.FileFormats/Graphics/VqaReader.cs

@@ -132,7 +132,7 @@ namespace OpenRA.FileFormats
 						// Don't parse sound (yet); skip data
 						{
 							var rawAudio = reader.ReadBytes((int)length);
-							audioData = AudLoader.LoadSound(rawAudio);
+							audioData = AudLoader.LoadSound(rawAudio, ref adpcmIndex);
 						}
 						break;
 					case "VQFR":
@@ -147,7 +147,9 @@ namespace OpenRA.FileFormats
 			}
 			if (++currentFrame == Frames)
 				currentFrame = cbOffset = cbChunk = 0;
-		}
+		}
+
+		int adpcmIndex = 0;
 		
 		// VQA Frame
 		public void DecodeVQFR(BinaryReader reader)