Medipen expansion

*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 medivends because there's no real brutekit.

![medipens](https://cloud.githubusercontent.com/assets/7812993/3507672/49511402-0681-11e4-8ebe-475ef60e8abb.PNG)

...also my first pull request, let's hope I didn't mess this up!