Armor Stands should be immune to attack damage

This would allow the player to use the armor stand as a 'training dummy' of sorts. They could be attacked and would still receive knockback, but would not break. Instead the player would need an axe or pickaxe to break them.

This would be a fun little quirk that would make the game feel just a little bit more alive. Plus, I could see myself hitting around an armor stand for hours (with a knockback II sword of course).