Makes reagent updates more event based, also makes plasma boil properly. (#54790)

Converts most on_reagent_change calls to signals.
Converts on_reagent_change to a signal handler.
Expands the reagent exposure signals
Add a setter proc and signal for reagent temperature
Fixes adjust_thermal_energy not sending a temperature change event
Makes min_temp and max_temp actually do something with adjust_thermal_energy

code/modules/mob/living/carbon/monkey/monkey.dm

@@ -57,6 +57,17 @@
 	SSmobs.cubemonkeys -= src
 	return ..()
 
+/mob/living/carbon/monkey/create_reagents(max_vol, flags)
+	. = ..()
+	RegisterSignal(reagents, list(COMSIG_REAGENTS_NEW_REAGENT, COMSIG_REAGENTS_DEL_REAGENT), .proc/on_reagent_change)
+	RegisterSignal(reagents, COMSIG_PARENT_QDELETING, .proc/on_reagents_del)
+
+/// Handles removing signal hooks incase someone is crazy enough to reset the reagents datum.
+/mob/living/carbon/monkey/proc/on_reagents_del(datum/reagents/reagents)
+	SIGNAL_HANDLER
+	UnregisterSignal(reagents, list(COMSIG_REAGENTS_NEW_REAGENT, COMSIG_REAGENTS_DEL_REAGENT, COMSIG_PARENT_QDELETING))
+	return NONE
+
 /mob/living/carbon/monkey/create_internal_organs()
 	internal_organs += new /obj/item/organ/appendix
 	internal_organs += new /obj/item/organ/lungs
@@ -69,8 +80,13 @@
 	internal_organs += new /obj/item/organ/stomach
 	..()
 
-/mob/living/carbon/monkey/on_reagent_change()
-	. = ..()
+/**
+ * Snowflake handling for morphine and nuka cola speed mods.
+ *
+ * Should be moved to the reagents at some future point. As it is I'm in a hurry.
+ */
+/mob/living/carbon/monkey/proc/on_reagent_change(datum/reagents/holder, ...)
+	SIGNAL_HANDLER
 	var/amount
 	if(reagents.has_reagent(/datum/reagent/medicine/morphine))
 		amount = -1
@@ -78,6 +94,7 @@
 		amount = -1
 	if(amount)
 		add_or_update_variable_movespeed_modifier(/datum/movespeed_modifier/monkey_reagent_speedmod, TRUE, amount)
+	return NONE
 
 /mob/living/carbon/monkey/updatehealth()
 	. = ..()

code/modules/mob/living/living_defense.dm

@@ -437,6 +437,7 @@
 		taste(source)
 
 	var/touch_protection = (methods & VAPOR) ? get_permeability_protection() : 0
+	SEND_SIGNAL(source, COMSIG_REAGENTS_EXPOSE_MOB, src, reagents, methods, volume_modifier, show_message, touch_protection)
 	for(var/reagent in reagents)
 		var/datum/reagent/R = reagent
 		. |= R.expose_mob(src, methods, reagents[R], show_message, touch_protection)

code/modules/mob/living/simple_animal/bot/secbot.dm

@@ -67,7 +67,6 @@
 	new /obj/item/stock_parts/cell/potato(Tsec)
 	var/obj/item/reagent_containers/food/drinks/drinkingglass/shotglass/S = new(Tsec)
 	S.reagents.add_reagent(/datum/reagent/consumable/ethanol/whiskey, 15)
-	S.on_reagent_change(ADD_REAGENT)
 	..()
 
 /mob/living/simple_animal/bot/secbot/pingsky

code/modules/mob/living/simple_animal/slime/slime.dm

@@ -113,6 +113,17 @@
 	Friends = null
 	return ..()
 
+/mob/living/simple_animal/slime/create_reagents(max_vol, flags)
+	. = ..()
+	RegisterSignal(reagents, list(COMSIG_REAGENTS_NEW_REAGENT, COMSIG_REAGENTS_DEL_REAGENT), .proc/on_reagent_change)
+	RegisterSignal(reagents, COMSIG_PARENT_QDELETING, .proc/on_reagents_del)
+
+/// Handles removing signal hooks incase someone is crazy enough to reset the reagents datum.
+/mob/living/simple_animal/slime/proc/on_reagents_del(datum/reagents/reagents)
+	SIGNAL_HANDLER
+	UnregisterSignal(reagents, list(COMSIG_REAGENTS_NEW_REAGENT, COMSIG_REAGENTS_DEL_REAGENT, COMSIG_PARENT_QDELETING))
+	return NONE
+
 /mob/living/simple_animal/slime/proc/set_colour(new_colour)
 	colour = new_colour
 	update_name()
@@ -142,8 +153,13 @@
 		icon_state = icon_dead
 	..()
 
-/mob/living/simple_animal/slime/on_reagent_change()
-	. = ..()
+/**
+ * Snowflake handling of reagent movespeed modifiers
+ *
+ * Should be moved to the reagents at some point in the future. As it is I'm in a hurry.
+ */
+/mob/living/simple_animal/slime/proc/on_reagent_change(datum/reagents/holder, ...)
+	SIGNAL_HANDLER
 	remove_movespeed_modifier(/datum/movespeed_modifier/slime_reagentmod)
 	var/amount = 0
 	if(reagents.has_reagent(/datum/reagent/medicine/morphine)) // morphine slows slimes down
@@ -152,6 +168,7 @@
 		amount = 5
 	if(amount)
 		add_or_update_variable_movespeed_modifier(/datum/movespeed_modifier/slime_reagentmod, multiplicative_slowdown = amount)
+	return NONE
 
 /mob/living/simple_animal/slime/updatehealth()
 	. = ..()