add dosbox.conf option (off by default) that if set, forces Sound
Blaster emulation to treat all DSP single-cycle playback commands as if
auto-init. This hack is a workaround for demos like Extreme's "lunatic"
demo that has problems responding to the Sound Blaster IRQ if under load
(including using DOSBox's speedlock function to "fast forward"). By
forcing auto-init playback, it no longer matters if the demo missed the
IRQ. Warnings are given in the config file that the option should not be
enabled unless necessary.