Balance tweaks

Based on Rogueliker's playthrough and some other observations, I've made some balance tweaks:

*  Ruffians are now a little braver.  They'll still run away, but the threshold before they do is tighter, so you may get in parting shots before they run now.  (PRO TIP: flintlocks are really nice for polishing off fleeing Ruffians and Buccaneers.)

*  Treasure chests that do not contain plot elements now generate 4x the amount of treasure.