arrange: Use object order list when arranging

Previously the stacking order was used. This meant that windows of the
same size after stacking changes might be shuffled around when doing e.g.
"desk arrange", which does not seem right.

src/arrange.c

@@ -731,7 +731,7 @@ ArrangeGetRectList(RectBox ** pfixed, int *nfixed, RectBox ** pfloating,
    fixed = floating = NULL;
    nfix = nflt = 0;
 
-   lst = EobjListStackGet(&num);
+   lst = EobjListOrderGet(&num);
    if (!lst)
       goto done;
 

src/eobj.h

@@ -204,6 +204,7 @@ void                EobjListFocusDel(EObj * eo);
 int                 EobjListFocusRaise(EObj * eo);
 void                EobjListOrderAdd(EObj * eo);
 void                EobjListOrderDel(EObj * eo);
+EObj               *const *EobjListOrderGet(int *num);
 
 /* Hmmm. */
 int                 OpacityFix(int op, int op_0);

src/stacking.c

@@ -509,6 +509,12 @@ EobjListOrderDel(EObj * eo)
    EobjListDel(&EobjListOrder, eo);
 }
 
+EObj               *const *
+EobjListOrderGet(int *num)
+{
+   return EobjListGet(&EobjListOrder, num);
+}
+
 EWin               *const *
 EwinListOrderGet(int *num)
 {