Feeding and squeaking tweaks (#681)

An extension based on live testing yesterday. 
Reduced the volume of mouse squeaks a bit, fixed Ian's automated feeding, and addded a couple new food related features to him

I made his scan delay drop when food is around, but scale up to a slower-than normal value if left alone, and added checking for held food. As well as tweaking some food-related vars on corgis

code/modules/reagents/reagent_containers/food/snacks.dm

@@ -16,7 +16,7 @@
 
 	//Placeholder for effect that trigger on eating that aren't tied to reagents.
 /obj/item/weapon/reagent_containers/food/snacks/proc/On_Consume(var/mob/M)
-	if(!usr)	return
+	if(!usr) usr = M
 	if(!reagents.total_volume)
 		M.visible_message("<span class='notice'>[M] finishes eating \the [src].</span>","<span class='notice'>You finish eating \the [src].</span>")
 		usr.drop_from_inventory(src)	//so icons update :[
@@ -3193,7 +3193,7 @@
 		reagents.add_reagent("imidazoline", 20)
 		reagents.add_reagent("hyperzine", 5)
 		bitesize = 5
-		
+
 //unathi snacks - sprites by Araskael
 
 /obj/item/weapon/reagent_containers/food/snacks/meatsnack