[ticket/11542] Add unit tests for language_select()

PHPBB3-11542
[ticket/11544] Add admin_login() method to 3.0 functional test case

This method is needed in order to be able to properly test acp functions.

PHPBB3-11544
[ticket/11542] Add lang_english_name to fixture

PHPBB3-11542
[ticket/11542] Add non-existing default value for language select

PHPBB3-11542
Merge remote-tracking branch 'nickvergessen/ticket/11542' into develop-olympus

* nickvergessen/ticket/11542:
  [ticket/11542] Add non-existing default value for language select
  [ticket/11542] Add lang_english_name to fixture
  [ticket/11542] Add unit tests for language_select()
[ticket/11547] Set MySQL charset to UTF8 in database_test_connection_manager.

PHPBB3-11547
Merge remote-tracking branch 'marc1706/ticket/11544' into develop-olympus

* marc1706/ticket/11544:
  [ticket/11544] Add admin_login() method to 3.0 functional test case
[ticket/11542] Use Czech as example as it contains non-latin characters

PHPBB3-11542
Merge remote-tracking branch 'nickvergessen/ticket/11542-2' into develop-olympus

* nickvergessen/ticket/11542-2:
  [ticket/11542] Use Czech as example as it contains non-latin characters
Merge remote-tracking branch 'bantu/ticket/11547' into develop-olympus

* bantu/ticket/11547:
  [ticket/11547] Set MySQL charset to UTF8 in database_test_connection_manager.