[1.1.5] Massive Blow prodigy: no bonus vs. undiggable walls

[jotwebe]

If you smack something against an undiggable wall with Massive Blow, you don't get the 350% damage multiplier you get when you smash something through a diggable wall. I think the extra damage should still be applied ("realistically" even more, but let's not overcomplicate things).

This probably applies as well to You Shall Be My Weapon, although I haven't tested that (see bug with both prodigies ignoring knockback immunity).