Fix camera getting stuck spectating itself (fixes #300)

This bug was introduced when we started to record the login phase because it
contains the UUID of the local player. In the replay case this will be the UUID
of the camera entity but also the one of the recording player, so if the
recording player despawns while it is being spectated (e.g. because of a
backwards jump), then the camera snaps onto itself and gets stuck in place until
one presses Shift.

src/main/java/com/replaymod/replay/camera/CameraEntity.java

@@ -80,6 +80,7 @@ import net.minecraft.client.render.entity.PlayerModelPart;
 //$$ import net.minecraft.util.Session;
 //#endif
 
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 import java.util.UUID;
 import java.util.function.Function;
@@ -99,6 +100,8 @@ public class CameraEntity
         //$$ extends EntityClientPlayerMP
         //#endif
 {
+    private static final UUID CAMERA_UUID = UUID.nameUUIDFromBytes("ReplayModCamera".getBytes(StandardCharsets.UTF_8));
+
     /**
      * Roll of this camera in degrees.
      */
@@ -155,6 +158,11 @@ public class CameraEntity
                 , false
                 //#endif
         );
+        //#if MC>=10900
+        setUuid(CAMERA_UUID);
+        //#else
+        //$$ entityUniqueID = CAMERA_UUID;
+        //#endif
         eventHandler.register();
         if (ReplayModReplay.instance.getReplayHandler().getSpectatedUUID() == null) {
             cameraController = ReplayModReplay.instance.createCameraController(this);