[MERGED PR] Purgatives and dialysis machine rebalance

[Lord_earthfire]

Keep in mind that changeling is currently by far the most common source of poisoning, this pr will affect changelings the most. Very strongly against the purgative changes, this is an incredibly large buff to changelings. Currently with calomel, if you inject it pretty quickly after you notice the effects, you can avoid being knocked out. This pr makes it to where in order to avoid being knocked out, you have to inject yourself with calomel literally the cycle that the effects become noticeable. This means that in the vast majority of cases, even with calomel, you will be knocked out. Keep in mind that calomel already deals lots of damage to you, this pr makes it to where using calomel now just gives you a bunch of damage and you get knocked out anyways. Changeling is already in the top 3 strongest antags when it comes to station wiping, they really dont need this buff.

I have no thoughts on the dialysis change

After this change, calomel is still equal to smelling salts, which should be the go-to used counter to changelings. (Curently purge of smelling salts: 3u/tick. Calomel: 5u/tick reduced to 3u/tick by this PR). Smeling salts have a lower decay, though.

This PR does neither removes nor makes the purgatives useless. It reduces their effect to more sensible values.