More daily fixes

So the jam is closed but I'm still chugging along. What I did today:

• The refactor I wanted to do. All boltdb-specific implementation code lives in one file and the abstract interfaces are a lot more clean. Now some other backing store/framework can drive the game transparently on the backend.
• Apparently I shipped a version where you could no longer take damage from enemies. Fixed that.
• Group together items by name in the inventory/items lists. You can now drop inventory items too.
• Scrolling/selection in inventory screen

Tomorrow I want to fix the equipment slots/equipping functionality. Still need to seed some Ice/Forest biome rules too.