Refactor /maps/ folder, this may break Travis

Tested and confirmed working, all expedition areas and POIs spawned correctly and as expected.

Added a new guide to help new contributors walk through adding new POIs or expedition areas, or gateway maps, in case the new system is confusing at all.

This will probably also break the following PR's:
https://github.com/VOREStation/VOREStation/pull/8807
https://github.com/VOREStation/VOREStation/pull/8558
https://github.com/VOREStation/VOREStation/pull/8820

maps/gateway_vr/snow_outpost.dm

@@ -0,0 +1,56 @@
+/obj/effect/overmap/visitable/sector/tether_gateway/snowoutpost
+	initial_generic_waypoints = list("tether_excursion_snow_outpost")
+	scanner_name = "Snowy Outpost"
+	scanner_desc = @{"[i]Stellar Body[/i]>: UNKNOWN
+[i]Class[/i]>: M-Class Planetoid
+[i]Habitability[/i]>: Moderate (Low Temperature)
+[b]Notice[/b]>: Various small outposts and extensive cave network detected on surface"}
+
+// -- Areas -- //
+
+/area/awaymission/snow_outpost
+	icon_state = "blank"
+	mobcountmax = 0
+	floracountmax = 0
+	base_turf = /turf/snow/snow2
+	ambience = list('sound/music/main.ogg', 'sound/ambience/maintenance/maintenance4.ogg', 'sound/ambience/sif/sif1.ogg', 'sound/ambience/ruins/ruins1.ogg')
+	base_turf = /turf/simulated/floor/snow/snow2
+
+/area/awaymission/snow_outpost/outside
+	icon_state = "away1"
+	always_unpowered = 1
+	dynamic_lighting = 0
+	mobcountmax = 50
+	floracountmax = 300
+	valid_mobs = list(/mob/living/simple_mob/animal/sif/savik, /mob/living/simple_mob/animal/wolf, /mob/living/simple_mob/animal/sif/shantak,
+					  /mob/living/simple_mob/animal/sif/kururak, /mob/living/simple_mob/animal/sif/frostfly)
+	valid_flora = list(/obj/structure/flora/tree/pine, /obj/structure/flora/tree/pine, /obj/structure/flora/tree/pine,
+					/obj/structure/flora/tree/dead, /obj/structure/flora/grass/brown, /obj/structure/flora/grass/green,
+					/obj/structure/flora/grass/both, /obj/structure/flora/bush, /obj/structure/flora/ausbushes/grassybush,
+					/obj/structure/flora/ausbushes/sunnybush, /obj/structure/flora/ausbushes/genericbush, /obj/structure/flora/ausbushes/pointybush,
+					/obj/structure/flora/ausbushes/lavendergrass, /obj/structure/flora/ausbushes/sparsegrass, /obj/structure/flora/ausbushes/fullgrass)
+
+/area/awaymission/snow_outpost/outside/EvalValidSpawnTurfs()
+	..()
+	if(mobcountmax || floracountmax)
+		for(var/turf/simulated/floor/water/W in src)
+			valid_spawn_turfs -= W
+		for(var/turf/simulated/floor/outdoors/ice/I in src)
+			valid_spawn_turfs -= I
+
+/area/awaymission/snow_outpost/dark
+	icon_state = "red"
+	requires_power = 1
+	always_unpowered = 1
+	dynamic_lighting = 1
+
+/area/awaymission/snow_outpost/outside/nospawn
+	icon_state = "away2"
+	mobcountmax = 0
+	floracountmax = 0
+
+/area/awaymission/snow_outpost/powered
+	requires_power = 0
+	dynamic_lighting = 1
+	icon_state = "away"
+	ambience = list('sound/ambience/chapel/chapel1.ogg', 'sound/ambience/ruins/ruins5.ogg', 'sound/ambience/ruins/ruins1.ogg')  // Rykka was here. <3