Arcane Robes and nerfed Durable: reduce first crit hit dmg

[jmegner]

Lifted from part of #7

To implement...

Durable chapter tactic from https://wahapedia.ru/kill-team2/kill-teams/intercession-squad/#Chapter-Tactics

Durable: Each time this operative fights in combat or a shooting attack is made against it, in the Resolve Successful Hits step of that combat or shooting attack, one critical hit inflicts one less damage on this operative (to a minimum of 3).

Arcane Robes equipment from https://wahapedia.ru/kill-team2/kill-teams/warpcoven/#Equipment

Arcane Robes: Once per battle, when Critical Damage would be inflicted upon this operative, you can use this ability. If you do so, that attack dice inflicts Normal Damage instead.

I think for shooting, these are fairly easy. For melee, it messes up some of the heuristics (strike if that will kill enemy, etc).

Note: Arcane Robes is "once per battle", so I would want to handle that when doing multi-round calcs, and it'd be good to correct that multi round bug for Just A Scratch as well.

[jmegner]

Durable implemented in commit 361889c.