Cannot configure FluidSynth settings in config file

[kotauskas]

FluidSynth's wealth of tunables, many of them instrumental to tolerable playback of many MIDIs (try listening to the Doom soundtrack with FluidSynth's default chorus setup, the synthesizer instruments are jarring), are currently not exposed by MPD in any way, with the only available configuration knob being the soundfont supplied to FluidSynth. I'd love to use the FluidSynth plugin, but as it is now, the lack of a way to supply -o options via entries in the decoder {…} section of the MPD config is a bit of a deal-breaker.