Entity::can_move_to checks Game.entities
Merge pull request #3 from Reaper42/something

Entity::can_move_to checks Game.entities
Some debug logging for Submap_pool
Don
Make Generic_map 3D.
Add a Dijkstra map function to Map for scent-like pathing to the player (or whatever).
Add a scent map to Game, update it each turn.
Rename Monster::target to Monster::entity_target
Pathfinding made 3D compliant (Straight line, A*)
Disable per-turn Dijkstra mapping for now - waaaay too slow.
Make monsters more three-dimensional; don't crash when they attempt 3D pathing.
New entity pathing system.  Very inefficient right now - it's an extreme rough draft and will improve shortly.
Merge issue
Add monster.cpp back
Make the standard rocky map have much fewer boulders.  Add several new rocky maps.
Add Map::set_movement_map() to make pathfinding faster
Fix an error in rocky.map
Fix some LOS stuff for map.
Prototype for a new entity AI system.
Make docs/ files .txt (see, I'm nice to Windows users!