Add invalidation for property source. Fix cache lock for scores.

Assets/Cryville/Crtr/PropSrc.cs

@@ -6,6 +6,7 @@ namespace Cryville.Crtr {
 	public abstract class PropSrc {
 		int _type;
 		byte[] _buf = null;
+		public void Invalidate() { _buf = null; }
 		public void Get(out int type, out byte[] value) {
 			if (_buf == null) InternalGet(out _type, out _buf);
 			type = _type;