Use -DPORTABLE=1 to build a portable version

When in none auth mode, registered users don't exist; hence the setting
makes the game impossible to join.

Normally the setting would be greyed out when the user is unregistered,
but commit 475c54bf introduced a new edge case where the stored setting
would apply to the field even if the user is unregistered, making the
setting possible to apply in no-reg mode. Regardless, any client could
have done this, not just the default cockatrice.

The server side fix should prevent all issues in the future.

Adds QCompleter in server room and a setting to enable/disable it.

This update address's the issue were a server with no db has only non-registered users but when creating a game will cause the dialogue to only allow the check box of "registered users only" resulting in a game that no user will ever be able to join.

When logging in and receiving a reply that isn't understood, show a more informative error message.

`tr() + tr()` for better translation flexibility.

See https://github.com/Cockatrice/Cockatrice/pull/1340 for details.

Moved setting files & Added code for a future portable build