To make xu4 modular, it must be possible to add new tiles,
and have visual representations of tiles be decoupled from tile rules.

- Explicitly map ULTIMA4 tileset indices to tile types.

- Currently tilemap-base.xml maps tile indices to tile names. 
	- A facility translates between these indices and names.
	- U4 uses tile indices for:
		Monster table (Save game)
		NPC types in townes
		Towne maps
		Overworld map
	- xu4 uses tile names for:
		xml files:
			- graphics
			- tileset-base:
				maps tile name to tile rule, specifies visuals
			- creatures
			- (more)

- GOAL Change tilemap-base
	Instead of 'base', call it 'ULTIMA4'
	Instead of 'tilemap', call it 'indexmap'
	The purpose of this file will be to associate indices in 'ULTIMA4' 
	dataset files to xu4 objects.
	
	1) Remove 'tile' attribute
	2) Add 'basetile' attribute to indicate a basetile name
			ie: terrain type
			eg: sea, water, shallows, swamp, etc.
	3) Add 'creature' attribute to indicate a creature name
			eg: mage, bard, lord_british, ettin
	4) Add 'object' attribute to indiate an object name
			eg: chest, door, bridge
	5) Add 'object_basetiles' attribute to indicate which 
		basetiles (comma-separated) should appear below an object.
		Default is 'brick_floor'.
		When multiple options are specified, the nearest match
		will be chosen.
		During map creation, a basetile is placed and the object
		is placed on top. If the object has tranparency, the
		basetile will show underneath. If the object is taken
		or opened, the basetile will also be visible.
		Note that this inference need only take place for ULTIMA4
		maps -- custom maps may use a unique format which may
		represent basetiles and objects differently.
					
- tileset-base.xml
	- Purpose is to map tile names to tile rules.
	- Animation and graphics details were bolted on 
	Goal:
	1)	Remove animation-based attributes:
		- 'animation' (move to graphics)
		- 'frames' (move to graphics)
		- 'usesReplacementTileAsBackground' (destroy!)
		- 'usesWaterReplacementTileAsBackground' (destroy!)
		- 'directions' (move to tile rules?)
	
-----------
In flux	
	- Change attributes:
		Flags
		- 'sailable'
		- 'swimmable'
		- 'walkable'
		
		- 'rule' (work with tilerules.xml!)
			- obstacle
				any decorative tile that cannot be traversed
			- water
				sea, water
			- shallows
			- swamp
			- grass
			- brush (assuming that forest is has same slow progress as brushland)
			- hills
			- mountains
			- settlement
			- civilization
			- entrance #ie: LBC entrance
			- bridge
			- solid
			- wall
		
		- 'opaque'
			- true
			- false (default)


U4 Map Tile Categories
======================
Base tiles:
	Basic tiles i.e., terrain, floors, etc.

Object tiles:
	Tiles which must infer a base tile and place an object on top.
			
Terrain base tiles (outdoors)
	- sea
	- water
	- shallows
	- swamp
	- grass
	- bush
	- forest
	- hills
	- mountains
	- lava
	- volcano

Land objects (outdoors)
	- dungeon 
		- attached to mountain
		- fully walkable
	- towne, castle, village, ruin, shrine
		- flat grass terrain with overlay
		- fully walkable
	- capital (LB castle, takes up 3 tiles)
		- flat grass terrain with overlay
		- left and right sections are not walkable
		- center is only north-enterable and south-exitable
	- left-right bridge of n length joins two walkable tiles
		- shallow water terrain with overlay
		- walkable on top (west, east)
		- swimmable underneath (north, south)
	- Special object
		- (e.g., ankh)
	
Additional base tiles (indoors)	
	
	
Restricted to indoors & battle:
-------------------------------

Structures
	- large bridge (top, bottom, wood)
	- brick road
	- large ship (i.e. battle screen)

Building components:
	- brickwall
	- stonewall
	- door (locked/unlocked/open)
	- secret door (hidden,occupied)
	- tables (countertops, letters, signs, etc.)
	- windows
	- ladders (up/down)
	- column
	- shipmast
	- shipwheel
	- altar
	- blackness
	- flooring:
		- brick
		- wood
		- tiled
	- throne (single and double)
	- elevated structure (i.e., the all-white tiles that have diagonals. Used in ships.)

Objects
	- rocks
	- magic field: PEFS (dispellable)
	- campfire
	- chest (gettable)
	- corpse

Misc
	- shield & sword (phantom tiles in minoc, can be considered 'statue')


Dungeon-only:
-------------
Objects
- Fountains
- Magical Balls
- Stone Altar
- Up/Down stairs.
