up ports the TG overlays subsystem update (#18945)

* up ports the TG overlays subsystem update

* .

* .

* .

* .

* for spell

* .

* cutting

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Co-authored-by: Cameron Lennox <killer65311@gmail.com>

code/__defines/overlay.dm

@@ -0,0 +1,26 @@
+// A reasonable number of maximum overlays an object needs
+// If you think you need more, rethink it
+#define MAX_ATOM_OVERLAYS 100
+
+/// Checks if an atom has reached the overlay limit, and make a loud error if it does.
+#define VALIDATE_OVERLAY_LIMIT(changed_on) \
+	if(length(changed_on.overlays) >= MAX_ATOM_OVERLAYS) { \
+		var/text_lays = overlays2text(changed_on.overlays); \
+		stack_trace("Too many overlays on [changed_on.type] - [length(changed_on.overlays)], refusing to update and cutting.\
+			\n What follows is a printout of all existing overlays at the time of the overflow \n[text_lays]"); \
+		changed_on.overlays.Cut(); \
+		changed_on.add_overlay(mutable_appearance('icons/Testing/greyscale_error.dmi')); \
+	} \
+
+/* Unneeded for now as our alternate appearances don't seem to support overlays in the same way TGs do.
+/// Performs any operations that ought to run after an appearance change
+#define POST_OVERLAY_CHANGE(changed_on) \
+	if(alternate_appearances) { \
+		for(var/I in changed_on.alternate_appearances){\
+			var/datum/atom_hud/alternate_appearance/AA = changed_on.alternate_appearances[I];\
+			if(AA.transfer_overlays){\
+				AA.copy_overlays(changed_on, TRUE);\
+			}\
+		} \
+	}
+*/

code/__defines/stat_tracking.dm

@@ -14,4 +14,4 @@
 	var/STAT_INCR_AMOUNT = min(1, 2**round((STAT_ENTRY[STAT_ENTRY_COUNT] || 0)/SHORT_REAL_LIMIT));\
 	if (STAT_INCR_AMOUNT == 1 || prob(100/STAT_INCR_AMOUNT)) {\
 		STAT_ENTRY[STAT_ENTRY_COUNT] += STAT_INCR_AMOUNT;\
-	};\
+	};