Exoplanet ruins, away sites, overmap submaps and maploader goodies. (#12933)

code/datums/ruins.dm

@@ -6,13 +6,19 @@
 	It is clearly a mystery."
 
 	var/spawn_weight = 1
-	var/cost = null
+	var/spawn_cost = 0
+	var/player_cost = 0
 	var/list/sectors = list() //This ruin can only spawn in the sectors in this list.
 
 	var/prefix = null
 	var/suffix = null
 	template_flags = 0 // No duplicates by default
 
+	// !! Currently only implemented for away sites
+	var/list/force_ruins // Listed ruins are always spawned unless disallowed by flags.
+	var/list/allow_ruins // Listed ruins are added to the set of available spawns.
+	var/list/ban_ruins   // Listed ruins are removed from the set of available spawns. Beats allowed.
+
 /datum/map_template/ruin/New()
 	if (suffix)
 		mappath += (prefix + suffix)