refactor 'dir = ' into 'set_dir()'

This should have little/no gameplay effect right now, just paving the
 way for directional lights.
Replaced handle_rotation() on buckly things with this.

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

code/modules/admin/topic.dm

@@ -1769,7 +1769,7 @@
 					else
 						var/atom/O = new path(target)
 						if(O)
-							O.dir = obj_dir
+							O.set_dir(obj_dir)
 							if(obj_name)
 								O.name = obj_name
 								if(istype(O,/mob))