Replace dumb with libopenmpt for MOD decoding

[sbooth]

https://lib.openmpt.org/libopenmpt/

[cherishloveyou]

Is this supported? How can I accurately know hich audio formats are currently supported

[sbooth]

MOD decoding is currently supported using DUMB but not libopenmpt.

There is not an exhaustive list of all formats supported but the README hits the highlights. The main reason there is not a complete list is Core Audio and libsndfile support multiple formats and Core Audio format support can change between operating system releases.