Livestock and fencing

[chrismdp]

• change chop trees to slash and burn type action with "makeshift tools"
• "build log fencing" a row of circles along one edge of a hex - exists along the edge of two hexes and is therefore in both spatial locations (somehow)
• allow sheep to wander the map and be captured through and action. Fences prevent them wandering in that direction.
• slaughter sheep action will beget a bit of raw meat that goes off that day