[b41] Shrugging off poison effect when poisoned removes it

[marvalis]

when you get poisoned by a trap, and you trigger the trap again,
when you shrug off the effect, the effect gets removed.

So this allows the player to remove poison by triggering the trap until he shrugs it off.

Shrugging of an effect should not remove previous effects.

[wobbly]

un-crippling an opponent is even worse

[wobbly]

bump

[wobbly]

rushing with a lightning-daze weapon gives particularly (un)amusing effects.