Nomad/doc

• The morale penalty is affected by time spent in overmap tiles up to 5 tiles away. Time in the current tile contributes fully, an overmap tile one tile away at 4/5, two away at 3/5, etc.
• The penalty starts at 12 hours accumulated, and hits max effect at 24 hours accumulated.
• The maximum morale penalty is -20.
• A tile is "forgotten" and fresh again after 7 days.