Remove melee retaliation from 1.5.6 randarts

I've suggested this before but its a big enough issue that I'd like to argue the point again.  This stat is vastly overused, it arbitrarily punishes melee and forces people to mouse over enemies to avoid dealing massive damage to themselves.  It should be limited to things where it is thematic and therefore expected.

The reason I think this should be done for 1.5.6 instead of waiting for 1.6 is the 1.5 change that made randarts not suck had the side effect of amplifying this problem, especially early game.  Randbosses are guaranteed to spawn with a rare, and its very possible for 1 rare to spawn with 2+ sources of melee retaliation damage.  This results in a boss that is not only extremely annoying or threatening for a wide variety of builds but drops an item that has stats nobody wants.  Not fun.

As a final point, these properties result in a *lot* of combat log spam.

If we must keep these properties I strongly suggest removing them for now and revisiting the issue in 1.6.

See merge request !493

Clarified online event option with three states, if you had changed the setting you need to reapply it

Fixed talent unlearning and item removal to correctly remove buffs they set like they already removed sustains