Refactored random map generator system and added several terrain generators.

Created a global list to track base turfs for explosions/shuttle moves.
Remaps the asteroid to be a moonlet. Tidies up some references to 'asteroid', removes moonbase from the accessible z level list.

code/modules/random_map/automata/automata.dm

@@ -0,0 +1,65 @@
+/datum/random_map/automata
+	descriptor = "generic caves"
+	initial_wall_cell = 55
+	var/iterations = 0               // Number of times to apply the automata rule.
+	var/cell_live_value = WALL_CHAR  // Cell is alive if it has this value.
+	var/cell_dead_value = FLOOR_CHAR // As above for death.
+	var/cell_threshold = 5           // Cell becomes alive with this many live neighbors.
+
+// Automata-specific procs and processing.
+/datum/random_map/automata/generate_map()
+	for(var/i=1;i<=iterations;i++)
+		iterate(i)
+
+/datum/random_map/automata/get_additional_spawns(var/value, var/turf/T)
+	return
+
+/datum/random_map/automata/proc/iterate(var/iteration)
+	var/list/next_map[limit_x*limit_y]
+	for(var/x = 1, x <= limit_x, x++)
+		for(var/y = 1, y <= limit_y, y++)
+			var/current_cell = get_map_cell(x,y)
+			next_map[current_cell] = map[current_cell]
+			var/count = 0
+
+			// Every attempt to place this in a proc or a list has resulted in
+			// the generator being totally bricked and useless. Fuck it. We're
+			// hardcoding this shit. Feel free to rewrite and PR a fix. ~ Z
+			var/tmp_cell = get_map_cell(x,y)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x+1,y+1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x-1,y-1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x+1,y-1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x-1,y+1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x-1,y)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x,y-1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x+1,y)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+			tmp_cell = get_map_cell(x,y+1)
+			if(tmp_cell && cell_is_alive(map[tmp_cell])) count++
+
+			if(count >= cell_threshold)
+				revive_cell(current_cell, next_map, (iteration == iterations))
+			else
+				kill_cell(current_cell, next_map, (iteration == iterations))
+	map = next_map
+
+// Check if a given tile counts as alive for the automata generations.
+/datum/random_map/automata/proc/cell_is_alive(var/value)
+	return (value == cell_live_value) && (value != cell_dead_value)
+
+/datum/random_map/automata/proc/revive_cell(var/target_cell, var/list/use_next_map, var/final_iter)
+	if(!use_next_map)
+		use_next_map = map
+	use_next_map[target_cell] = cell_live_value
+
+/datum/random_map/automata/proc/kill_cell(var/target_cell, var/list/use_next_map, var/final_iter)
+	if(!use_next_map)
+		use_next_map = map
+	use_next_map[target_cell] = cell_dead_value

code/modules/random_map/automata/caves.dm

@@ -0,0 +1,52 @@
+/datum/random_map/automata/cave_system
+	iterations = 5
+	descriptor = "moon caves"
+	wall_type =  /turf/simulated/mineral
+	floor_type = /turf/simulated/floor/plating/airless/asteroid
+	target_turf_type = /turf/unsimulated/mask
+	var/mineral_sparse =  /turf/simulated/mineral/random
+	var/mineral_rich = /turf/simulated/mineral/random/high_chance
+	var/list/ore_turfs = list()
+
+/datum/random_map/automata/cave_system/get_appropriate_path(var/value)
+	switch(value)
+		if(DOOR_CHAR)
+			return mineral_sparse
+		if(EMPTY_CHAR)
+			return mineral_rich
+		if(FLOOR_CHAR)
+			return floor_type
+		if(WALL_CHAR)
+			return wall_type
+
+/datum/random_map/automata/cave_system/get_map_char(var/value)
+	switch(value)
+		if(DOOR_CHAR)
+			return "x"
+		if(EMPTY_CHAR)
+			return "X"
+	return ..(value)
+
+/datum/random_map/automata/cave_system/revive_cell(var/target_cell, var/list/use_next_map, var/final_iter)
+	..()
+	if(final_iter)
+		ore_turfs |= target_cell
+
+/datum/random_map/automata/cave_system/kill_cell(var/target_cell, var/list/use_next_map, var/final_iter)
+	..()
+	if(final_iter)
+		ore_turfs -= target_cell
+
+// Create ore turfs.
+/datum/random_map/automata/cave_system/cleanup()
+	var/ore_count = round(map.len/20)
+	while((ore_count>0) && (ore_turfs.len>0))
+		if(!priority_process) sleep(-1)
+		var/check_cell = pick(ore_turfs)
+		ore_turfs -= check_cell
+		if(prob(75))
+			map[check_cell] = DOOR_CHAR  // Mineral block
+		else
+			map[check_cell] = EMPTY_CHAR // Rare mineral block.
+		ore_count--
+	return 1