Banning doesn't work with weird nicknames

[elexis]

Users can mess with their nickname to prevent the host from kicking/banning them. The first letter of the nickname must be a character that the host can't type (hence autocomplete won't work).

The lobby already has some rules in place, testing for allowed characters. But when joining via IP, the nicknames can have leading whitespace and completely arbitrary characters (including combining operators which only modify the following character, messing up even the strings that show the names).

Thanks Hannibal Barca for investigating.

While the username could be sanitized when joining the match, it would prevent for example chinese users to play with chinese names. Better solve this issue by allowing to ban users by clicking on them in a new window. Internally, the GUID should be passed to the engine.

[elexis]

(set component to network)

[elexis]

With lobby authentication in alpha 23, the problem now only exists if someone uses an account registered with a different xmpp client and weird characters. #3787 should make this obsolete altogether.

It may still be reasonable to add a default.cfg option to restrict playernames to certain charactersets. For example ascii-only, arab or asian characters and no restrictions.

[elexis]

#3787 allows banning everyone by selecting.

It would be cleaner to pass a GUID instead of a playername nonetheless, but that is kind of self-evident, an enhancement and not a defect and unrelated to reported issue.