this would allow for underground wagons which would rock 
not sure best way to make it possible...but figured id get the ball rolling
1.a new craftable something like animal harness that you can use like a rope to "leash" the animal and then right click it on the minehole and it sends the animal down
2.you can lift all baby animals and then be able to carry them through the minehole or cave entrance (i think there would be problems here since they need a parents milk to survive, correct me if im wrong there)
