With that, it is possible to restore the full "instance" from a backup
made with mariadb-dump --dir

The patch implements executing DDL (tables, views, triggers) using
statements that are stored in .sql file, created by mariadb-dump
--dir .

Care is taken of creating triggers correctly after the data is loaded,
disabling foreign keys and unique key checks etc.

The files are loaded in descending order by datafile size -
to ensure better work distribution when running with --parallel option.

In addition to --dir option, following options are implemented for
partial restore

include-only options:
--database             -  import one or several databases
--table                -  import one or several tables

exclude options:
--ignore-database      -. ignore one or several databases when importing
--ignore-table         -  to ignore one or several tables when importing

All options above are only valid together with --dir option,
and can be specified multiple times.