Fix FluidSynth mode and polyphony

[ceski-1]

This PR sets midi-bank-select and polyphony values to their defaults: gs and 256, respectively.

PrBoom+ used to have typos that meant default values were used for midi-bank-select and polyphony and that was fine. 495fd59 fixed the typos, so PrBoom+ started using poorly chosen values that cause notes to drop or cut out and disables GS features if a MIDI file uses them.

Download this: polyphony.zip

prboom-plus.exe -iwad doom2.wad -file polyphony.wad -warp 1

Listen to the trombone that plays in the left channel. If it cuts out, the polyphony is set too low.

References:

• Doomworld post
• midi-bank-select
• polyphony

[fabiangreffrath]

Thank you!