Abstract machinery, intercom listener, and directional hardhat lights (#1918)

changes:

Added an abstract-machinery helper type for interacting with power systems without duplicating power code.
Changed intercoms to use abstract machines to handle power state changes instead of polling with process().
Hardhat lights are now directional (LIGHT_WIDE)
Fixes #1922.

code/modules/clothing/head/hardhat.dm

@@ -8,6 +8,7 @@
 	armor = list(melee = 30, bullet = 5, laser = 20,energy = 10, bomb = 20, bio = 10, rad = 20)
 	flags_inv = 0
 	siemens_coefficient = 0.9
+	light_wedge = LIGHT_WIDE
 
 /obj/item/clothing/head/hardhat/orange
 	icon_state = "hardhat0_orange"