vmware svga2 IRQ sharing
IRQ: early EOI

kernel/idt.s:
	send EOI before calling handlers, since they may use IRQs themselves,
	such as calling disk io.
Implement ES1371 AudioPCI'97.

kernel/dev.s:
	declare sound base class - extending from dev_pci since no multiple
	inheritance.

kernel/es1371.s:
	Implement initialisation and audio playback.
	Implement class_sound.

kernel/sb.s:
	Objectify: declare sb extends sound and implement.
	move cmd_sb to shell.s as cmd_play.

kernel/shell.s:
	rename cmd_sb to cmd_play.
	Use OO sound API to play files.