Fix vanilla entity update packet handling (fixes #607)

src/main/java/com/replaymod/replay/ext/EntityExt.java

@@ -0,0 +1,9 @@
+package com.replaymod.replay.ext;
+
+public interface EntityExt {
+    float replaymod$getTrackedYaw();
+    void replaymod$setTrackedYaw(float value);
+
+    float replaymod$getTrackedPitch();
+    void replaymod$setTrackedPitch(float value);
+}