Add an ability to drop .sf2 files

[paperluigis]

Basically an ability to load in custom soundfonts for MIDI files.

[mmontag]

This would be nice, especially for just trying stuff out.

In the long term, I am tempted to make a separate web MIDI player project with more room for features, and without the limitation of the DOS theme. With a nice piano roll visualizer and the ability to do MIDI routing per-channel.

[mmontag]

Hi @paperluigis, you can now drop SF2 files.