refactor buckling to be more generic

Buckling procs and vars have been moved down to /obj.
Behaviour is mostly the same, but you can buckle cuffed people to
 pipes and they will automatically unbuckle if the cuffs are removed.

Signed-off-by: Mloc-Argent <colmohici@gmail.com>

code/game/objects/items/weapons/implants/implantfreedom.dm

@@ -23,6 +23,8 @@
 			if (source.handcuffed)
 				var/obj/item/weapon/W = source.handcuffed
 				source.handcuffed = null
+				if(source.buckled && source.buckled.buckle_require_restraints)
+					source.buckled.unbuckle_mob()
 				source.update_inv_handcuffed()
 				if (source.client)
 					source.client.screen -= W