Update to armadillo curl hitbox

It would be very useful for map-makers if the Armadillo's hitbox acted as a solid block in the same way that a Shulker's does, because as it stands right now, the Shulker isn't the greatest way to make solid, movable platforms or walls considering that it's impossible to turn its head invisible without shaders. 

This could also be a great opportunity to rework the physics of such hitboxes, because as it stands right now, they are very buggy. For example, standing on a shulker that is moving upwards is extremely buggy, and sometimes running at or standing on a shulker that is peeking out can also be really buggy.