This mostly reverts #6937 by making our `IOHANDLE` effectively `FILE *` on all systems again. We still use `CreateFileW` to open a `HANDLE` initially so we can specify the necessary flag so the file can be moved/deleted while open, which we can't do with the `FILE *` based `fopen` functions on Windows. This brings back the automatic I/O buffering on Windows, causing significantly less system calls when saving files. Closes#7226.
Simplify the handling of free texture indices by using `-1` only for indices which are currently in use, whereas the size of the vector is now used to indicate the last free index. Otherwise the assertions incorrectly detect the last texture index always being in use because `-1` was used for both states.
Previously, if the demo header strings did not contain zero-termination, the client would render the strings and any following non-zero memory from the demo header.
Now, demos will not be loaded, if any string in the header is not zero-terminated or not valid UTF-8.
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.