Smoke problems fix

This PR intends to fix smoke problems without actually making smoke much less deadly overall. This PR:
1) Lowers the amount wood feeds a fire. This stops heavy sticks and 2x4's from instantly creating a raging fire on their own. It also slightly reduces duration of said fires (2 hours to ~1.5), but I feel having the fire stay at a proper density of 1 outweighs that.
2) Increased the negative age needed to go from density 2->3. This makes the gap between a density 2 and 3 slightly larger.
3) Made density 1 smoke less deadly, players now have a 50% chance to be infected for 2 turns instead of a 100% chance to be infected for 3.
4) Added a minimum disease duration needed before coughing. This makes short trips through light smoke or 1 turn in medium smoke possible without causing coughing

This PR also:
1) Fixes an erroneous coughing message.
2) Cleans up some logic in the coughing function.