awful.util.get_rectangle_in_direction(): Use pairs

This code works just fine with non-integer table keys. Also, this is used by
awful.screen.focus_bydirection() and thus will be used with screen objects
instead of screen indicies when we get rid of screen indicies.

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/util.lua

@@ -362,7 +362,7 @@ function util.get_rectangle_in_direction(dir, recttbl, cur)
     local target = nil
 
     -- We check each object
-    for i, rect in ipairs(recttbl) do
+    for i, rect in pairs(recttbl) do
         -- Check geometry to see if object is located in the right direction.
         if is_in_direction(dir, cur, rect) then
             -- Calculate distance between current and checked object.