disease.cpp reformat, drug effect rebalance and realism tweaks, new related items and item descriptions.

I'd like to finish refactoring that big switch statement into a new class, but I was thinking that it should be in a new branch.

* Reformatted disease.cpp and moved some parts of the big disease switch to separate functions.
* Edited item descriptions for most of the drugs.
  * Renamed marijuana to "cannabis" and marijuana seeds to "hemp seeds."
* Rebalanced some drugs' effects, prices, spawn frequencies or other properties.
* Added glass and tobacco pipes, and rolling papers as smoking implements.
  * Cannabis use now requires a smoking implement and a flame.
* Added cannabis high as a separate disease type which bionic blood analysis can identity.
* Linked cannabis usage with reduced vomiting frequency in players with Weak Stomach/Nausea traits.
* Added addiction potentials to several drugs which should have them.