Add msn_weights

Add the new zip which is the weight files of the MSN model on ETH-UCY and SDD.
Note Since the x-y coordinates of ETH-hotel were in the opposite order of those in the repository during previous training, a new parameter msn_hotel_fix is added to correct this problem by adding preprocessing scale and rotate.
For hotel dataset, you can run by

python main.py --model MKII --loada a_hotel --loadb l