Flags and adjacency work (#20259)

Added a bunch of flags for passflags on things that were previously
missing them.
Removed snowflake passthrow var, it's a passflag now.
Updated ClickCross and Adjacency code.
It's now possible to interact with things that are adjacent but
otherwise have a machine (or other appropriate items) blocking them, eg.
think of an APC on the wall with a machine in front of it.

code/game/objects/structures/barricades/_barricade.dm

@@ -3,7 +3,6 @@
 	climbable = TRUE
 	anchored = TRUE
 	density = TRUE
-	throwpass = TRUE //You can throw objects over this, despite its density.
 	atom_flags = ATOM_FLAG_CHECKS_BORDER
 
 	var/stack_type //The type of stack the barricade dropped when disassembled if any.

code/game/objects/structures/crates_lockers/closets.dm

@@ -6,7 +6,7 @@
 	density = TRUE
 	build_amt = 2
 	slowdown = 5
-	pass_flags_self = PASSTRACE
+	pass_flags_self = PASSSTRUCTURE | LETPASSCLICKS | PASSTRACE
 
 	var/icon_door = null
 	/// Override to have open overlay use icon different to its base's

code/game/objects/structures/grille.dm

@@ -8,6 +8,7 @@
 	icon_state = "grille"
 	density = TRUE
 	anchored = TRUE
+	pass_flags_self = PASSGRILLE
 	obj_flags = OBJ_FLAG_CONDUCTABLE | OBJ_FLAG_MOVES_UNSUPPORTED
 	explosion_resistance = 1
 	layer = BELOW_WINDOW_LAYER

code/game/objects/structures/morgue.dm

@@ -143,7 +143,7 @@
 	icon_state = "morguet"
 	density = TRUE
 	anchored = TRUE
-	throwpass = TRUE
+	pass_flags_self = PASSSTRUCTURE | LETPASSTHROW
 	layer = BELOW_OBJ_LAYER
 	obj_flags = OBJ_FLAG_MOVES_UNSUPPORTED
 	var/obj/structure/morgue/connected = null

code/game/objects/structures/plasticflaps.dm

@@ -3,8 +3,9 @@
 	desc = "Completely impassable - or are they?"
 	icon = 'icons/obj/structure/plasticflaps.dmi'
 	icon_state = "plasticflaps_preview"
-	density = 0
-	anchored = 1
+	density = FALSE
+	anchored = TRUE
+	pass_flags_self = PASSSTRUCTURE | PASSFLAPS
 	layer = UNDERDOOR
 	explosion_resistance = 5
 	build_amt = 4

code/game/objects/structures/railing.dm

@@ -4,7 +4,6 @@
 	icon = 'icons/obj/structure/blocker/railing_basic.dmi'
 	icon_state = "railing0-1"
 	density = TRUE
-	throwpass = TRUE
 	climbable = TRUE
 	layer = OBJ_LAYER
 	anchored = FALSE

code/game/objects/structures/urban.dm

@@ -431,9 +431,9 @@ ABSTRACT_TYPE(/obj/structure/stairs/urban/road_ramp)
 	icon = 'icons/obj/structure/urban/blockers.dmi'
 	icon_state = "rod_railing"
 	density = TRUE
-	throwpass = TRUE
-	climbable = TRUE
 	anchored = TRUE
+	pass_flags_self = PASSSTRUCTURE | LETPASSTHROW
+	climbable = TRUE
 
 /obj/structure/rod_railing/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 	if(mover?.movement_type & PHASING)
@@ -463,8 +463,8 @@ ABSTRACT_TYPE(/obj/structure/stairs/urban/road_ramp)
 	icon = 'icons/obj/structure/urban/blockers.dmi'
 	icon_state = "dam1"
 	density = TRUE
-	throwpass = TRUE
 	anchored = TRUE
+	pass_flags_self = PASSSTRUCTURE | LETPASSTHROW
 
 /obj/structure/road_barrier
 	name = "roadway barrier"
@@ -472,7 +472,7 @@ ABSTRACT_TYPE(/obj/structure/stairs/urban/road_ramp)
 	icon = 'icons/obj/structure/urban/road_edges.dmi'
 	icon_state = "guard"
 	density = TRUE
-	throwpass = TRUE
+	pass_flags_self = PASSSTRUCTURE | LETPASSTHROW
 	climbable = TRUE
 	anchored = TRUE
 

code/game/objects/structures/window.dm

@@ -11,6 +11,7 @@
 	icon_state = "window"
 	alpha = 196
 	density = TRUE
+	pass_flags_self = PASSWINDOW
 	w_class = WEIGHT_CLASS_NORMAL
 	layer = SIDE_WINDOW_LAYER
 	anchored = TRUE