[ticket/12809] Fix select button and dropdown list items in RTL.

PHPBB3-12809
[ticket/12809] Remove obsolete rules and selector.

PHPBB3-12809
[ticket/12809] Restore text-align for the pagination.

PHPBB3-12809
[ticket/12932] Add method for getting the datetime class and allow overriding

An extension can now override the datetime class by overwriting the
datetime.class parameter in their own yml file.

PHPBB3-12932
[ticket/12932] Fix tests and calls to create_datetime

PHPBB3-12932
[ticket/12932] Remove set_datetime_class method from user class

PHPBB3-12932
Merge pull request #2862 from marc1706/ticket/12932

[ticket/12932] Add method for allowing override of \phpbb\datetime class

* marc1706/ticket/12932:
  [ticket/12932] Remove set_datetime_class method from user class
  [ticket/12932] Fix tests and calls to create_datetime
  [ticket/12932] Add method for getting the datetime class and allow overriding
[ticket/12931] Fix general error on user registration

Fix "Illegal use of $_SERVER" general error on user registration
when $config['server_name'] is not set.

PHPBB3-12931
[ticket/12964] Correct use of undefined $row variable.

PHPBB3-12964
Merge pull request #2714 from prototech/ticket/12809

[ticket/12809] Fix select button and dropdown list items in RTL.
Merge pull request #2864 from rxu/ticket/12931

[ticket/12931] Fix general error on user registration
Merge pull request #2866 from bantu/ticket/12964

[ticket/12964] Correct use of undefined $row variable.