Whitelisting to bypass the reroute system.

Note, all ckeys in the ofwhitelist must be lowercase and contain no
spaces.

code/controllers/configuration.dm

@@ -81,8 +81,7 @@
 	var/forumurl = "http://baystation12.net/forums/"
 
 	var/media_base_url = "http://nanotrasen.se/media" // http://ss13.nexisonline.net/media
-	var/overflow_server_url = "byond://nanotrasen.se:6666"
-
+	var/overflow_server_url
 	var/forbid_singulo_possession = 0
 
 	//game_options.txt configs
@@ -156,6 +155,7 @@
 	var/starlight = 0	// Whether space turfs have ambient light or not
 	var/allow_holidays = 0
 	var/player_overflow_cap = 0 //number of players before the server starts rerouting
+	var/list/overflow_whitelist = list() //whitelist for overflow
 
 /datum/configuration/New()
 	var/list/L = typesof(/datum/game_mode) - /datum/game_mode
@@ -654,6 +654,19 @@
 			else
 				diary << "Unknown setting in configuration: '[name]'"
 
+/datum/configuration/proc/loadoverflowwhitelist(filename)
+	var/list/Lines = file2list(filename)
+	for(var/t in Lines)
+		if(!t)	continue
+
+		t = trim(t)
+		if (length(t) == 0)
+			continue
+		else if (copytext(t, 1, 2) == "#")
+			continue
+
+		config.overflow_whitelist += t
+
 /datum/configuration/proc/pick_mode(mode_name)
 	// I wish I didn't have to instance the game modes in order to look up
 	// their information, but it is the only way (at least that I know of).