Sanity exploit fixing (#59)

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## About The Pull Request
<details>
<summary>
Prevents players from injecting water and nutriment into food items with
syringes. This behaviour was involved in an infinite sanity/insight
exploit that allowed massive powerleveling. Players who attempt to
inject water or nutriment into food items will be met with a line of
text reading "Adding [reagent] to [the food] seems like it would ruin
it." and no reagents from the syringe will be added. Other reagents,
including poisons, toxins, tar, and medicines, can be added. This will
make the exploit a LOT harder or remove it entirely.

Additionally, fixed Individual Objectives providing a level up one
minute after completing objectives, allowing for massive powerleveling.
Objectives will now reward around 25 insight only.
</summary>
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</details>

## Changelog
<!-- fixed: Powerleveling bugs. -->

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code/datums/objective/individual_objective/individual_objective.dm

@@ -65,7 +65,7 @@
 	update_faction_score()
 	to_chat(owner,  SPAN_NOTICE("You have completed the personal objective: [name]"))
 	H.sanity.give_insight(insight_reward)
-	H.sanity.finish_rest()
+	//H.sanity.finish_rest()	//Uncommenting this line causes anyone to gain a level one minute after they finish the personal objective. Please. Please do not release this.
 
 /datum/individual_objective/proc/get_description()
 	var/n_desc = desc

code/modules/reagents/reagent_containers/syringes.dm

@@ -225,6 +225,20 @@
 								to_chat(user, "<span class='[pain > 50 ? "danger" : "warning"]'>Your amateur actions caused you [pain > 50 ? "a lot of " : ""]pain.</span>")
 				else
 					to_chat(target, SPAN_NOTICE("You feel a tiny prick!"))
+			if(istype(target, /obj/item/reagent_containers/food/snacks))
+				var/cheesecheck = FALSE
+				var/blamereagent
+				var/list/blacklistedreagents = list("water", "nutriment")
+				for(var/datum/reagent/R in src.reagents.reagent_list)
+					if(R.id in blacklistedreagents)
+						cheesecheck = TRUE
+						blamereagent = R.id
+						continue
+				if(cheesecheck)
+					to_chat(user, "Adding [blamereagent] to [target] seems like it would ruin it.")
+					return
+				else
+					trans = reagents.trans_to(target, amount_per_transfer_from_this)
 			else
 				trans = reagents.trans_to(target, amount_per_transfer_from_this)
 			to_chat(user, SPAN_NOTICE("You inject [trans] units of the solution. [src] now contains [src.reagents.total_volume] units."))