[ticket/12655] Run the shell when --shell is used

PHPBB3-12655
[ticket/12655] Don't require acp/common again in the commands

PHPBB3-12655
[ticket/12655] Set the arguments of \phpbb\console\application as required

PHPBB3-12655
[ticket/12655] Fix coding style in \phpbb\console\application

PHPBB3-12655
[ticket/12655] Make the --shell option available only for phpbbcli.php

PHPBB3-12655
[ticket/12655] Fix coding style

PHPBB3-12655
Merge pull request #2543 from Nicofuma/ticket/12655

[ticket/12655] Run phpbbcli as a shell when --shell or -s is used

* Nicofuma/ticket/12655:
  [ticket/12655] Fix coding style
  [ticket/12655] Make the --shell option available only for phpbbcli.php
  [ticket/12655] Fix coding style in \phpbb\console\application
  [ticket/12655] Set the arguments of \phpbb\console\application as required
  [ticket/12655] Don't require acp/common again in the commands
  [ticket/12655] Run the shell when --shell is used