UTF-8 support for usernames #41437
Description
Currently, usernames are limited to ASCII, which is unfortunate and restrictive. To make Owncloud suitable for international language use, usernames should be relaxed to UTF-8. Owncloud would be the first software capable of doing this, which would set Owncloud apart from other self-hosting applications for clouds.
Proprietary clouds are also limited to ASCII in user names, which would make Owncloud a more attractive alternative. This is particularly true in China, Japan, India and Europe.
In order not to jeopardise existing data, UTF-8 activation should only be possible via an explicit setting, with a warning that this may result in the loss of plugins. This prevents anyone from accidentally creating UTF-8 usernames.