TG: Fixed projectiles going into disposals.

Made the rapid syringe gun a subtype of the syringe gun, and reduced it's
capacity to four syringes.
Fixed the examine bug on syringe guns.
Added a new sprite for the regular syringe gun.

Added a new door for research. It's also used in robotics.

Updated the air injector sprite.

Fixed some pepperspray spelling errors.

~~REMOVED~~: the energy crossbow and chemsprayer from R&D.

code/modules/recycling/disposal.dm

@@ -478,6 +478,8 @@
 	CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 		if (istype(mover,/obj/item))
 			var/obj/item/I = mover
+			if(istype(I, /obj/item/weapon/dummy) || istype(I, /obj/item/projectile))
+				return
 			if(!mover.throwing)
 				return ..()
 			if(prob(75))