part_recs_slow() -> part_records();
HTON_SUPPORTS_SYS_VERSIONING -> HTON_NATIVE_SYS_VERSIONING.

Closes #204

IB: Fixes in logic when to do versioned or usual row updates. Now it is
able to do unversioned updates for versioned tables just by disabling
`TABLE_SHARE::versioned` flag.

SQL: DDL tracking for:
* RENAME TABLE, ALTER TABLE .. RENAME TO;
* DROP TABLE;
* data-modifying operations (f.ex. ALTER TABLE .. ADD/DROP COLUMN).

Test is main.mysqldump