Rebalance: Medicine produces five units from two plants.

Closes GH #45
Fix 'separate bone' bolt-making reactions. Thanks to GTrax.

See discussion and fix at
http://www.bay12forums.com/smf/index.php?topic=125628.msg4836436#msg4836436
Merge branch 'master' into nerfed_diseases

* master:
  Fix 'separate bone' bolt-making reactions. Thanks to GTrax.
  Rebalance: Medicine produces five units from two plants.