Makes showers wash away touching reagents

Also moves reagent permeability to it's own proc, and makes splash_mob respect copy

code/game/objects/structures/watercloset.dm

@@ -225,6 +225,12 @@
 		if(M.back)
 			if(M.back.clean_blood())
 				M.update_inv_back(0)
+		
+		//flush away reagents on the skin
+		if(M.touching)
+			var/remove_amount = M.touching.maximum_volume * M.reagent_permeability() //take off your suit first
+			M.touching.remove_any(remove_amount)
+		
 		if(ishuman(M))
 			var/mob/living/carbon/human/H = M
 			var/washgloves = 1