Issue #4 - Porting resize (micro/macro) systems.

* Instead of "playerscale" we are using pre-existing variable
 "size_multiplier" but we move it to /mob/living
* Added basic mechanics of size changing.
* Mousetraps snap small people even if they have shoes.
* Big people can walk over small people, or stomp them, or capture them
 in foot slot.
* Ported holder for micros, making small people scoopable.
* Tied held micros in with the vore code so they are edible.
* Ported size-altering reagents and recipies.
* Ported size gun along with associated sprites and sounds.

code/modules/assembly/mousetrap.dm

@@ -28,11 +28,11 @@
 			var/mob/living/carbon/human/H = target
 			switch(type)
 				if("feet")
-					if(!H.shoes)
+					if(!H.shoes || H.get_effective_size() < RESIZE_SMALL)
 						affecting = H.get_organ(pick("l_leg", "r_leg"))
 						H.Weaken(3)
 				if("l_hand", "r_hand")
-					if(!H.gloves)
+					if(!H.gloves || H.get_effective_size() < RESIZE_SMALL)
 						affecting = H.get_organ(type)
 						H.Stun(3)
 			if(affecting)