New directional beach sprites and corners for the 2018 Summer Ball (#38262)

* Adds beach corners, interior corners, and other sides in addition to the normal down direction.

* SOMEONE LIED TO ME

* Update misc_plating.dm

* don't copy paste at 4am

* okay there we go

code/game/turfs/simulated/floor/plating/misc_plating.dm

@@ -119,6 +119,9 @@
 	icon_state = "water"
 	baseturfs = /turf/open/floor/plating/beach/water
 
+/turf/open/floor/plating/beach/coastline_t/sandwater_inner
+	icon_state = "sandwater_inner"
+	baseturfs = /turf/open/floor/plating/beach/coastline_t/sandwater_inner
 
 /turf/open/floor/plating/ironsand
 	name = "iron sand"