Making coke from wood no longer creates ash.

Wood blocks/planks to coke no longer has a 20% chance of producing ash.

Instead, the player has to choose whether they want coke or ash from planks.
(Similar the to wood oven.)

Players may also burn a wood log to 3 ash.

Split commit from 7be2d976d21e6ade4ed9b15b3d8af4780e6aaf10

GH #101
Rebalance: Medicine now makes 3 potions from 1 stack of plants

Previously this was 5 potions from two stacks.

Split commit from 7be2d976d21e6ade4ed9b15b3d8af4780e6aaf10

GH #101