Per the tracker issue:
> In 3.1 a youtube profilefield was added in which we can insert our youtube
> username to link to it.... There is just one major problem though...
>
> New youtube members no longer get an username. So I think we should decide on
> providing different ways to access their profile.
This PR will allow users to use any valid YouTube-domain URL, which allows for
all 3 formats (`/channel/...`, `/c/...`, and the now-legacy `/user/...`).
Per [YouTube's docs](https://support.google.com/youtube/answer/6180214?hl=en):
> ## Channel URL (ID-based)
> Example: youtube.com/channel/UCUZHFZ9jIKrLroW8LcyJEQQ
>
> This is the standard URL that YouTube channels use.
>
> ...
>
> ## Custom URL
> Example: youtube.com/c/YouTubeCreators
>
> A custom URL is a shorter, easy-to-remember URL that you can share with your
> audience.
>
> ...
>
> ## Legacy username URL
> Example: youtube.com/user/YouTube
>
> Depending on when your channel was created, it may have a username. Usernames
> are no longer required for channels today, but you can still use this URL to
> direct to your channel — even if your channel name has changed since you chose
> your username. Existing usernames can't be changed.
PHPBB3-13859
Currently AbstractPostgreSQLDriver requires Postgres platform to be an instance
of PostgreSQL94Platform. When this will be changed in Doctrine,
this fix can be reverted.
PHPBB3-16964
MSSQL:
- Fix bool type
- Fix comparator
- Drop Default constraint before deleting column
- Rename Default constraint to use phpBB's names
- Re-create the indices when changing the type of one column
- Uses varchar instead of varbinary
PostgreSQL:
- Creates auto increment sequences by hand instead of using serial
in order to use phpBB's names
- Drop constraint on unique / primary indices
Oracle:
- Rename indices to use phpBB's names
- Fix string not null behaviour
- Fix broken regex in Oracle driver
- Handle to long indices on Oracle
- Rename auto_increment trigger and sequence
- Automatically lowercase keys in assoc results
PHPBB3-16741
