Revert "12/21 modernizations from TG live"

code/datums/diseases/_MobProcs.dm

@@ -19,6 +19,9 @@
 	if(!(type in D.viable_mobtypes))
 		return 0
 
+	if(count_by_type(viruses, /datum/disease/advance) >= 3)
+		return 0
+
 	return 1
 
 
@@ -29,30 +32,23 @@
 
 
 /mob/proc/AddDisease(datum/disease/D)
-	for(var/datum/disease/advance/P in viruses)
-		if(istype(D, /datum/disease/advance))
-			var/datum/disease/advance/DD = D
-			if (P.totalResistance() < DD.totalTransmittable()) //Overwrite virus if the attacker's Transmission is lower than the defender's Resistance. This does not grant immunity to the lost virus.
-				P.remove_virus()
+	var/datum/disease/DD = new D.type(1, D, 0)
+	viruses += DD
+	DD.affected_mob = src
+	DD.holder = src
 
-	if (!viruses.len) //Only add the new virus if it defeated the existing one
-		var/datum/disease/DD = new D.type(1, D, 0)
-		viruses += DD
-		DD.affected_mob = src
-		DD.holder = src
+	//Copy properties over. This is so edited diseases persist.
+	var/list/skipped = list("affected_mob","holder","carrier","stage","type","parent_type","vars","transformed")
+	for(var/V in DD.vars)
+		if(V in skipped)
+			continue
+		if(istype(DD.vars[V],/list))
+			var/list/L = D.vars[V]
+			DD.vars[V] = L.Copy()
+		else
+			DD.vars[V] = D.vars[V]
 
-		//Copy properties over. This is so edited diseases persist.
-		var/list/skipped = list("affected_mob","holder","carrier","stage","type","parent_type","vars","transformed")
-		for(var/V in DD.vars)
-			if(V in skipped)
-				continue
-			if(istype(DD.vars[V],/list))
-				var/list/L = D.vars[V]
-				DD.vars[V] = L.Copy()
-			else
-				DD.vars[V] = D.vars[V]
-
-		DD.affected_mob.med_hud_set_status()
+	DD.affected_mob.med_hud_set_status()
 
 
 /mob/living/carbon/ContractDisease(datum/disease/D)
@@ -86,7 +82,7 @@
 
 	var/target_zone = pick(head_ch;1,body_ch;2,hands_ch;3,feet_ch;4)
 
-	if(ishuman(src))
+	if(istype(src, /mob/living/carbon/human))
 		var/mob/living/carbon/human/H = src
 
 		switch(target_zone)
@@ -97,9 +93,6 @@
 				if(passed && isobj(H.wear_mask))
 					Cl = H.wear_mask
 					passed = prob((Cl.permeability_coefficient*100) - 1)
-				if(passed && isobj(H.wear_neck))
-					Cl = H.wear_neck
-					passed = prob((Cl.permeability_coefficient*100) - 1)
 			if(2)
 				if(isobj(H.wear_suit))
 					Cl = H.wear_suit
@@ -124,7 +117,7 @@
 					Cl = H.shoes
 					passed = prob((Cl.permeability_coefficient*100) - 1)
 
-	else if(ismonkey(src))
+	else if(istype(src, /mob/living/carbon/monkey))
 		var/mob/living/carbon/monkey/M = src
 		switch(target_zone)
 			if(1)
@@ -147,6 +140,6 @@
 
 
 /mob/living/carbon/human/CanContractDisease(datum/disease/D)
-	if(dna && (VIRUSIMMUNE in dna.species.species_traits))
+	if(dna && (VIRUSIMMUNE in dna.species.specflags))
 		return 0
 	return ..()