Ratvar speech is now misheard correctly

Previously it was displaying as clockwork scarab says "", because of a
runtime in the rot13() function. I fixed it.

Also fixes the maptext for debug GPS units.

code/__HELPERS/text.dm

@@ -462,9 +462,10 @@ var/list/rot13_lookup = list()
 	var/t_out = ""
 
 	for(var/i in 1 to length(t_in))
-		if(i in rot13_lookup)
-			t_out += rot13_lookup[i]
+		var/char = copytext(t_in, i, i + 1)
+		if(char in rot13_lookup)
+			t_out += rot13_lookup[char]
 		else
-			t_out += i
+			t_out += char
 
 	return t_out

code/modules/telesci/gps.dm

@@ -138,7 +138,7 @@ var/list/GPS_list = list()
 		// I assume it's faster to color,tag and OR the turf in, rather
 		// then checking if its there
 		T.color = RANDOM_COLOUR
-		T.maptext = "[x],[y],[z]"
+		T.maptext = "[T.x],[T.y],[T.z]"
 		tagged |= T
 
 /obj/item/device/gps/visible_debug/proc/clear()