* play non-MIDI music with SDL for all music backends
* fallback to SDL by default
* implement Fluidsynth music backend
* fix mus_chorus
* set samplerate
* use Fluidsynth's player functions for pause/resume
* little cleanup
* fix initialization of SDL music backend, cleanup
* add missing static
* fix the -nosfx parameter, cosmetic changes
* remove obsolete header files from CMakeLists.txt
* add missing static
* fix some MSVC warnings
* use midiStreamPause function
* reuse IsMid and IsMus functions