When using `auth_remove`, the key indices for the default helper, mod and admin passwords were not properly adjusted, causing the wrong passwords to be used for the username-less logins.
The key indices for connected clients were also not properly adjusted, causing the wrong identity to be shown for currently authenticated clients when using the `status` command.
Closes#6427.
Most variables used in the sound engine were static globals, as they are used in the static sound mixing function. The global variables are replaced by member variables, by passing the sound interface as user-data for the SDL mixing callback. The `Mix` function is made a public member function of `ISound` instead of being exposed using `ISoundMixFunc GetSoundMixFunc()`.
This allows to remove the direct dependency of the engine sound on the engine video, by instead passing the sound mixing function as a lambda to the engine video in the engine client.
The old WavPack reader function interface does support passing a user-data pointer to the callback function, so global variables are still used here.
Respect the intratick when displaying the player position, speed and angle, to fix this information always being shown for the next tick. See #6417. This does not resolve the issue yet, as there are more HUD and player elements that need to make use of the intratick.
Fix highlighted text of server browser entries not being refresh correctly when switching tabs.
This also reduces lag when switching tabs, as the UI elements for all tabs are now cached and don't need to be recreated when switching.
Regression from #7203.
Replace existing hard-coded support for two "networks" with support for a dynamic list of "communities" which are indexed by a string-ID, though right now the DDNet and KoG communities are still hard-coded. The communities now also support an arbitrary number of associated countries, types and servers. This is a refactoring to prepare for getting the list of communities dynamically from the server and removing the DDNet and KoG tabs from the serverbrowser.
New UI elements were being created for every server info after refreshing the server list. At the same time, old UI elements were not being deleted when the server info objects are deleted. The use of `mutable` for this purpose was also rather unclean.
Now, a separate `std::vector` of UI elements is kept for all server browser entries, instead of associating the UI elements directly with the server info.