First version of new authentification procedure: now authentification is one-stage (instead of two-stage in 4.1)

For now following tasks have been done:
- PASSWORD() function was rewritten. PASSWORD() now returns SHA1
  hash_stage2; for new passwords user.password contains '*'hash_stage2; sql_yacc.yy also fixed; 

- password.c: new functions were implemented, old rolled back to 4.0 state

- server code was rewritten to use new authorization algorithm (check_user(), change
  user, and other stuff in sql/sql_parse.cc)

- client code was rewritten to use new authorization algorithm
  (mysql_real_connect, myslq_authenticate in sql-common/client.c)

- now server barks on 45-byte-length 4.1.0 passwords and refuses 4.1.0-style
  authentification. Users with 4.1.0 passwords are blocked (sql/sql_acl.cc)

- mysqladmin.c was fixed to work correctly with new passwords

Tests for 4.0-4.1.1, 4.1.1-4.1.1 (with or without db/password) logons was performed;
mysqladmin also was tested. Additional check are nevertheless necessary.

sql/sql_class.h

@@ -529,10 +529,16 @@ public:
   enum_tx_isolation session_tx_isolation;
   /* for user variables replication*/
   DYNAMIC_ARRAY user_var_events;
-             // extend scramble to handle new auth
-  char	     scramble[SCRAMBLE41_LENGTH+1];
-             // old scramble is needed to handle old clients
-  char       old_scramble[SCRAMBLE_LENGTH+1];
+
+  /* scramble - random string sent to client on handshake */
+  char	     scramble[SCRAMBLE_LENGTH+1];
+  /*
+    The same as scramble but for old password checking routines. It always
+    contains first N bytes of scramble.
+    See check_connection() at sql_parse.cc for authentification details.
+  */
+  char       scramble_323[SCRAMBLE_LENGTH_323+1];
+
   uint8	     query_cache_type;		// type of query cache processing
   bool       slave_thread;
   bool	     set_query_id,locked,count_cuted_fields,some_tables_deleted;