tweaks to vermin spawning

Signed-off-by: Cael_Aislinn <cael_aislinn@yahoo.com.au>

code/modules/critters/critters.dm

@@ -164,6 +164,7 @@
 	atkcarbon = 1
 	atksilicon = 0
 	attacktext = "bites"
+	layer = 2.1		//so they can hide under objects
 
 	Bump(var/mob/M)
 		if(ishuman(M))

code/modules/mob/simple_animal/mouse.dm

@@ -18,6 +18,7 @@
 	response_harm   = "splats the"
 	density = 0
 	var/color	//brown, gray and white
+	layer = 2.1		//so they can hide under objects
 
 /mob/living/simple_animal/mouse/Life()
 	..()