Removed hex_dm.lua
Styles : temp workaround to rename "caves" style to "naturals" (in lieu of
renaming it in the GUI code and global style table...)
Removed most of existing planner.lua code (not needed here)
Removed 'caves.lua' and 'automata.lua' -- not needed here.
Tidied up Levels_build_it() function.
Removed ht_fabs.lua -- not needed here.
Removed the old connection logic (incl. the branch generator functions)
Fix for ht_fabs removal.
Removed most of the old room-handling code (in room.lua)
Removed most of the old layout logic (in layout.lua)
Implemented code to detect the "inner points" of each area, i.e. the grid
points which lie completely inside the area (not touching the boundary).
(debug : temp disable void areas)
Start room choosing : take '#inner_points' into account.
Start room : never in a hallway!
Better hallway logic -- evaluate based on new 'openness' measure (and size too).
Began work on new logic for deciding area kinds (outdoor / natural / etc).
This commit has code for picking the starting area.
Fleshed out the 'spread_kind' algorithm.
Logic to decide quota (seeds and starts) for spreading Outdoor and Natural
area groups.  Also convert results to a proper "kind" field.
New area kind logic : improved quota logic and various fixes.
(undo debug stuff...)