Implements building restrictions (by terrain, territory, category, and distance). See #41. Fixes #804, #287.
Implements build limits. See #687.
Implements autorotation for dock placement.
Fixes unit spawning to consider terrain passability. See #893.
Adds new passability criteria based on distance from shore.
Updates build restrictions on some templates.
Changes unit spawning search to 4 tiles away from foundation.
Changes garrison/training spawn failure to nicer UI notification.