This isn't the final location but this means that the device is merely a data provider, with the sole exception of the Win32 MIDI device whose unwieldy usage requirements unfortunately dictate much of the needed interface here.
This also removes the OPL dumper because I wasn't able to get any non-broken output from it and have no desire to fix such a niche feature.
# Conflicts:
# src/sound/mididevices/music_opldumper_mididevice.cpp
src\sound\mididevices\music_opl_mididevice.cpp(112): error C3861: 'I_DebugPrint': identifier not found
src\sound\mididevices\music_opl_mididevice.cpp(206): error C3861: 'I_DebugPrint': identifier not found
src\sound\mididevices\music_opl_mididevice.cpp(234): error C3861: 'I_DebugPrint': identifier not found
src\sound\mididevices\music_opl_mididevice.cpp(244): error C3861: 'I_DebugPrint': identifier not found
The idea here is to decouple the actual reader creation from the code using them so that, for example, the Open function can decide if it wants to open the file regularly or memory mapped and return different readers as deemed useful. For that to work the exposed object needs to be an abstract wrapper so that this can be done without having to use pointers and all the drawbacks coming from that.
So far put to use in a few parts of the music code so the general functionality could be tested.
This was done after the players had already been created. To ensure that everything gets set properly it is necessary to pass the desired sample rate to the device's constructor and let it make sure that a proper sample rate gets set.
