[ticket/11525] Only remove group or user prefix from given avatar data

Until now, the user data had both user_id and group_id keys in the avatar
data. As both group_ and user_ prefixes were removed the group_id was
collapsed onto the user_id and therefore all users in the same group had
the same prefix for their uploaded avatars. This patch will make sure
that the correct id is used depending on whether it's a group's or user's
avatar data.

PHPBB3-11525
[ticket/11998] Add symfony/console as dependency.

PHPBB3-11998
[ticket/11998] Basic console application script.

PHPBB3-11998
[ticket/11998] Use container to get all commands using 'console.command' tag.

PHPBB3-11998
[ticket/11998] Also setup extension class loader.

PHPBB3-11998
[ticket/11998] Add console command for recalculating email hash.

PHPBB3-11998
[ticket/11943] Add test for DEFINE $VAR = false

PHPBB3-11943
[ticket/11943] Do not quote the value when it is exactly true, false, or null

Quoting these can change the meaning of the value (e.g. 'false' == true)

PHPBB3-11943
[ticket/11998] Move application file to bin/phpbbcli.php

PHPBB3-11998
[ticket/11998] Add phpBB abstraction for application and command.

PHPBB3-11998
[ticket/11998] Turn develop/extensions.php into console commands.

PHPBB3-11998
[ticket/11927] Correctly add new files on update

Currently we ignore language and style files when the directory where they
go to do not exist. However in 3.1 we introduce some new sub directories:
* language/en/email/short/
* styles/prosilver/theme/en/
So we need to change our check to look whether the language or style exist,
rather then the parent directory.

PHPBB3-11927
[ticket/11927] Add doc block to new function

PHPBB3-11927
[ticket/11927] Prefix function with phpbb_

PHPBB3-11927
[ticket/11994] Make extension manager UI less misleading

Enable and Install were split into two different expressions.
Purge was renamed to uninstall to make clearer what is going to happen.

PHPBB3-11994
[ticket/11994] More language fixes

PHPBB3-11994
[ticket/11994] Fix functional extension tests

PHPBB3-11994
[ticket/11994] Replace spaces with tabs

PHPBB3-11994
[ticket/11994] Fix some language

PHPBB3-11994
[ticket/11994] Use display name on confirmation screen

PHPBB3-11994