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.
Purely automatic change. In case of conflict with this change, apply the
other change and rerun the formatting to restore it:
$ python scripts/fix_style.py
- videorecorder only works for recording demos now
- demoplayer was modified to allow controll over the time that passed
in order to get perfect fps, IVideo controlls how much time passed,
basically every rendercall sets the time to record the next frame