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/__defines/subsystem-defines.dm

@@ -28,6 +28,18 @@
 #define TIMER_ID_NULL -1
 
 // -- SSatoms stuff --
+// Technically this check will fail if someone loads a map mid-round, but that's not enabled right now.
+#define SSATOMS_IS_PROBABLY_DONE (SSatoms.initialized == INITIALIZATION_INNEW_REGULAR)
+
+//type and all subtypes should always call Initialize in New()
+#define INITIALIZE_IMMEDIATE(X) ##X/New(loc, ...){\
+    ..();\
+    if(!initialized) {\
+        args[1] = TRUE;\
+        SSatoms.InitAtom(src, args);\
+    }\
+}
+
 // 	SSatoms Initialization state.
 #define INITIALIZATION_INSSATOMS 0	//New should not call Initialize
 #define INITIALIZATION_INNEW_MAPLOAD 1	//New should call Initialize(TRUE)