storage: rename 'obj.*serial' columns to '*tid' for consistency with 'trans' table

UPGRADE

@@ -9,10 +9,10 @@ SQL commands to migrate each storage from NEO 0.10.x::
   CREATE TABLE new_data (id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, hash BINARY(20) NOT NULL UNIQUE, compression TINYINT UNSIGNED NULL, value LONGBLOB NULL) ENGINE = InnoDB SELECT DISTINCT obj.hash as hash, compression, value FROM obj, data WHERE obj.hash=data.hash ORDER BY serial;
   DROP TABLE data;
   RENAME TABLE new_data TO data;
-  CREATE TABLE new_obj (partition SMALLINT UNSIGNED NOT NULL, oid BIGINT UNSIGNED NOT NULL, serial BIGINT UNSIGNED NOT NULL, data_id BIGINT UNSIGNED NULL, value_serial BIGINT UNSIGNED NULL, PRIMARY KEY (partition, serial, oid), KEY (partition, oid, serial), KEY (data_id)) ENGINE = InnoDB SELECT partition, oid, serial, data.id as data_id, value_serial FROM obj LEFT JOIN data ON (obj.hash=data.hash);
+  CREATE TABLE new_obj (partition SMALLINT UNSIGNED NOT NULL, oid BIGINT UNSIGNED NOT NULL, tid BIGINT UNSIGNED NOT NULL, data_id BIGINT UNSIGNED NULL, value_tid BIGINT UNSIGNED NULL, PRIMARY KEY (partition, tid, oid), KEY (partition, oid, tid), KEY (data_id)) ENGINE = InnoDB SELECT partition, oid, serial as tid, data.id as data_id, value_serial as value_tid FROM obj LEFT JOIN data ON (obj.hash=data.hash);
   DROP TABLE obj;
   RENAME TABLE new_obj TO obj;
-  ALTER TABLE tobj CHANGE hash data_id BIGINT UNSIGNED NULL;
+  ALTER TABLE tobj CHANGE serial tid BIGINT UNSIGNED NOT NULL, CHANGE hash data_id BIGINT UNSIGNED NULL, CHANGE value_serial value_tid BIGINT UNSIGNED NULL;
 
 NEO 0.10
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