[NEEDS BALANCING] Make traumakit painkillers contribute to stim OD

[MarinaGryphon]

Each use of anaesthetic counts as ¹/₂₀ᵗʰ of a stim use, as outlined in #117.
HOWEVER: This means that using one stim and 4 anaesthetics will put you at the OD threshold, because a stim is 400 stimcount and the overdose is at 480 stimcount. I think this should probably be tweaked somewhat, or there should be a way to tell if you're too close to the OD limit to safely use anaesthetics. When I play, I try to ration my painkillers and only use them on things that need a lot of biofoam or obstructions (and only use two full doses for something with both), but I think this might become a noob trap.
One potential idea is to make stims themselves act as a low-level anaesthetic for all wounds, so that anaesthetic is less necessary if you've already used one, but that might just make it so that the meta is using only stims instead. If there are any other ideas on how to balance this, I'd like to hear them.

[caligari87]

After some consideration, I think 1/100th of a stim would be more in line with what I was intending. That would allow 20 local injections (a "full stim" worth) back-to-back after injecting an actual stim, without overdose (but very close to it).

I'm definitely on-board with having stims provide low-level painkiller effects as well and have talked about it several times, though overall pain management in the trauma kit is all over the board as-is and probably needs rebalancing anyway.