Implements reaction-over-time and reaction yield

code/controllers/Processes/chemistry.dm

@@ -0,0 +1,33 @@
+var/datum/controller/process/chemistry/chemistryProcess
+
+/datum/controller/process/chemistry
+	var/tmp/datum/updateQueue/updateQueueInstance
+	var/list/active_holders
+	var/list/chemical_reactions
+	var/list/chemical_reagents
+
+/datum/controller/process/chemistry/setup()
+	name = "chemistry"
+	schedule_interval = 20 // every 2 seconds
+	updateQueueInstance = new
+	chemistryProcess = src
+	active_holders = list()
+	chemical_reactions = chemical_reactions_list
+	chemical_reagents = chemical_reagents_list
+
+/datum/controller/process/chemistry/getStatName()
+	return ..()+"([active_holders.len])"
+
+/datum/controller/process/chemistry/doWork()
+	for(var/datum/reagents/holder in active_holders)
+		if(!holder.process_reactions())
+			active_holders -= holder
+		scheck()
+
+/datum/controller/process/chemistry/proc/mark_for_update(var/datum/reagents/holder)
+	if(holder in active_holders) 
+		return
+
+	//Process once, right away. If we still need to continue then add to the active_holders list and continue later
+	if(holder.process_reactions())
+		active_holders += holder