Yet another representation for arrays

This "linear" representation (see ltable.h for details) has worse
locality than cells, but the simpler access code seems to compensate
that.

lobject.h

@@ -773,15 +773,12 @@ typedef union Node {
 #define setnorealasize(t)	((t)->flags |= BITRAS)
 
 
-typedef struct ArrayCell ArrayCell;
-
-
 typedef struct Table {
   CommonHeader;
   lu_byte flags;  /* 1<<p means tagmethod(p) is not present */
   lu_byte lsizenode;  /* log2 of size of 'node' array */
   unsigned int alimit;  /* "limit" of 'array' array */
-  ArrayCell *array;  /* array part */
+  Value *array;  /* array part */
   Node *node;
   struct Table *metatable;
   GCObject *gclist;