More initialize tweaks (#2971)

changes:

Organs now use Initialize().
The observe message now shows the configured respawn delay instead of always 30 minutes.
Seed datums no longer have a timer in New().
External organs no longer have a timer in New()/Initialize()
Converted some spawns in organs to timers.
Floor init no longer breaks to plating first for mapped in tiles.
Added the INITIALIZE_IMMEDIATE macro to make Initialize() not wait for SSatoms init.
Mannequins now use INITIALIZE_IMMEDIATE instead of a custom-defined New().
Mannequins (from get_mannequin) now delete themselves if unused for 5 minutes or longer.

code/modules/mob/living/carbon/brain/brain_item.dm

@@ -32,12 +32,15 @@
 	icon = 'icons/mob/alien.dmi'
 	icon_state = "chitin"
 
-/obj/item/organ/brain/New()
-	..()
+/obj/item/organ/brain/Initialize(mapload)
+	. = ..()
 	health = config.default_brain_health
-	spawn(5)
-		if(brainmob && brainmob.client)
-			brainmob.client.screen.len = null //clear the hud
+	if (!mapload)
+		addtimer(CALLBACK(src, .proc/clear_screen), 5)
+
+/obj/item/organ/brain/proc/clear_screen()
+	if (brainmob && brainmob.client)
+		brainmob.client.screen.Cut()
 
 /obj/item/organ/brain/Destroy()
 	if(brainmob)

code/modules/mob/living/carbon/human/human_species.dm

@@ -2,11 +2,7 @@
 	real_name = "Test Dummy"
 	status_flags = GODMODE|CANPUSH
 
-/mob/living/carbon/human/dummy/mannequin/New(location, ...)
-    ..()
-    if (!initialized)
-        args[1] = TRUE
-        SSatoms.InitAtom(src, args)
+INITIALIZE_IMMEDIATE(/mob/living/carbon/human/dummy/mannequin)
 
 /mob/living/carbon/human/dummy/mannequin/Initialize()
 	. = ..()

code/modules/mob/new_player/new_player.dm

@@ -114,13 +114,13 @@
 		new_player_panel_proc()
 
 	if(href_list["observe"])
-		if (SSatoms.initialized < INITIALIZATION_INNEW_REGULAR)
+		if (!SSATOMS_IS_PROBABLY_DONE)
 			// Don't allow players to observe until initialization is more or less complete.
 			// Letting them join too early breaks things, they can wait.
-			src << span("alert", "The server is still initializing, try observing again in a minute or so.")
-			return
+			alert(src, "Please wait, the map is not initialized yet.")
+			return 0
 
-		if(alert(src,"Are you sure you wish to observe? You will have to wait 30 minutes before being able to respawn!","Player Setup","Yes","No") == "Yes")
+		if(alert(src,"Are you sure you wish to observe? You will have to wait [config.respawn_delay] minutes before being able to respawn!","Player Setup","Yes","No") == "Yes")
 			if(!client)	return 1
 			var/mob/dead/observer/observer = new /mob/dead/observer(src)
 			spawning = 1