Refactors the map generation to not assume the fifth z-level is mining. Now it checks the config.txt.

code/controllers/configuration.dm

@@ -141,6 +141,8 @@ var/list/gamemode_cache = list()
 	var/welder_vision = 1
 	var/generate_asteroid = 0
 
+	var/asteroid_z_levels = list()
+
 	//Used for modifying movement speed for mobs.
 	//Unversal modifiers
 	var/run_speed = 0
@@ -329,6 +331,12 @@ var/list/gamemode_cache = list()
 				if ("generate_asteroid")
 					config.generate_asteroid = 1
 
+				if ("asteroid_z_levels")
+					config.asteroid_z_levels = text2list(value, ";")
+					//Numbers get stored as strings, so we'll fix that right now.
+					for(var/z_level in config.asteroid_z_levels)
+						z_level = text2num(z_level)
+
 				if("allow_admin_ooccolor")
 					config.allow_admin_ooccolor = 1