Fix some issues with changing player viewheight at runtime

- Viewheight change was delayed: Viewheight must be copied to player
  structure as well as the PlayerPawn. Not sure if should actually use
  deltaviewheight to spread the change out over a few tics instead of
  being instant.
- Viewheight not preserved when travelling: player->viewheight must be
  restored from pawn->ViewHeight, because the temporary player set it back
  to the default viewheight.

src/fragglescript/t_cmd.cpp

@@ -169,6 +169,7 @@ void FS_EmulateCmd(char * string)
 			{
 				// No, this is not correct. But this is the way Legacy WADs expect it to be handled!
 				if (players[i].mo != NULL) players[i].mo->ViewHeight = playerviewheight;
+				players[i].viewheight = playerviewheight;
 				players[i].Uncrouch();
 			}
 			while (sc.GetString())