Ports weapons cleaving and reaching features from polaris (#3969)

-axes, chainswords and longswords can now cleave, hitting targets around the user, ported from polaris
-added support for melee weapons that can hit targets two titles away, as well ported from polaris

code/_onclick/click.dm

@@ -125,7 +125,7 @@
 	// A is a turf or is on a turf, or in something on a turf (pen in a box); but not something in something on a turf (pen in a box in a backpack)
 	sdepth = A.storage_depth_turf()
 	if(isturf(A) || isturf(A.loc) || (sdepth != -1 && sdepth <= 1))
-		if(A.Adjacent(src)) // see adjacent.dm
+		if(A.Adjacent(src) || (W && W.attack_can_reach(src, A, W.reach)) ) // see adjacent.dm
 			setMoveCooldown(5)
 
 			if(W)

code/_onclick/item_attack.dm

@@ -23,8 +23,13 @@ avoid code duplication. This includes items that may sometimes act as a standard
 /obj/item/proc/attack_self(mob/user)
 	return
 
+// Called at the start of resolve_attackby(), before the actual attack.
+/obj/item/proc/pre_attack(atom/a, mob/user)
+	return
+
 //I would prefer to rename this to attack(), but that would involve touching hundreds of files.
 /obj/item/proc/resolve_attackby(atom/A, mob/user)
+	pre_attack(A, user)
 	add_fingerprint(user)
 	return A.attackby(src, user)