*Adds 4 new medipen variants: Bicaridine, Kelotane, Antitoxin(Dylovene) and Dexalin, each with their own sprite including inhands! The basic medipen also has a new sprite.
*Medipens now hold 15u and inject 5u per use but are still impossible to refill.
*Replaced all kelotane pills in the burn kit with kelotane medipens.
*Replaced two dexalin pills in the o2 kit with dexalin medipens.
*Replaced all antitoxin syringes in the antitox kit with antitox medipens.
*Added 4 bicaridine medipens to the large medivend.

...also my first pull request, let's hope I didn't mess this up.
Rebalancing and a bugfix.