Table definition cache, part 2

The table opening process now works the following way:
- Create common TABLE_SHARE object
- Read the .frm file and unpack it into the TABLE_SHARE object
- Create a TABLE object based on the information in the TABLE_SHARE
  object and open a handler to the table object

Other noteworthy changes:
- In TABLE_SHARE the most common strings are now LEX_STRING's
- Better error message when table is not found
- Variable table_cache is now renamed 'table_open_cache'
- New variable 'table_definition_cache' that is the number of table defintions that will be cached
- strxnmov() calls are now fixed to avoid overflows
- strxnmov() will now always add one end \0 to result
- engine objects are now created with a TABLE_SHARE object instead of a TABLE object.
- After creating a field object one must call field->init(table) before using it

- For a busy system this change will give you:
 - Less memory usage for table object
 - Faster opening of tables (if it's has been in use or is in table definition cache)
 - Allow you to cache many table definitions objects
 - Faster drop of table

sql/ha_federated.h

@@ -173,7 +173,7 @@ private:
   int stash_remote_error();
 
 public:
-  ha_federated(TABLE *table_arg);
+  ha_federated(TABLE_SHARE *table_arg);
   ~ha_federated() {}
   /* The name that will be used for display purposes */
   const char *table_type() const { return "FEDERATED"; }
@@ -232,8 +232,7 @@ public:
   */
   double scan_time()
   {
-    DBUG_PRINT("info",
-               ("records %d", records));
+    DBUG_PRINT("info", ("records %lu", (ulong) records));
     return (double)(records*1000); 
   }
   /*