ZAS Performance Improvements (#2308)

This PR converts ZAS' c_airblock procs into a single macro for performance reasons, as well as allows CanPass to be bypassed for atoms that do not require special air blocking behavior.

Appears to have a significant effect on performance, needs more detailed testing.

Some objects are likely missing canpass flags, I only set the obvious ones. Please comment if you find one I missed.

Might fix #2152.

code/modules/shieldgen/energy_field.dm

@@ -13,6 +13,8 @@
 	var/strength = 0
 	var/ticks_recovering = 10
 
+	atmos_canpass = CANPASS_NEVER
+
 /obj/effect/energy_field/New()
 	..()
 	update_nearby_tiles()