Vim regain & disease powers

[Fhtagn]

I've noticed that neither the reaver/corruptor diseases, nor cyst burst, nor catalepsy return their vim cost when killing an enemy with them (that's in b41, though).
As far as I can tell by the changelogs for b42 and b43, this should still be the case.
I'm not sure wether this is intended or not; either way, I think a fix/change would be in order.

That lack of regain makes using diseases kind of tedious and caused my reaver to basically run around with ±0 vim half the time, thus making boss fights where I'd arrive with no vim usually quite a bit more challenging than they'd have needed to be. Other than that, I really like diseases. The spreading mechanics and aoe power are definitely fun to play with.