Automatically downgrade utf8mb4_900_* collations to utf8mb4_unicode_520_ci on MariaDB. MariaDB does not support the utf8mb4_900_* (Unicode 9.x) family of collations used by modern versions of Joomla!. It only supports the older utf8mb4_*_520_ci (Unicode 5.2) family of collations. In practice, very little would be lost when downgrading from Unicode 9 to 5.2; it's mainly newer Emoji, and some rarely used characters. The restoration script will now automatically convert your tables to this older collation automatically when transferring a site from a MySQL to a MariaDB server.
Bug fixes and minor improvements. Please take a look at the CHANGELOG below.