GXemul Code2

Rewrote/refactored enough of the dec_ioasic code to make the 5000/125 original PROM output its first boot messages again (and NetBSD/pmax and OpenBSD/pmax too).

DECstation 5000/125 "3MIN" mode has been broken for quite a while; attempting to rewrite/resurrect it.

Updating the Sprite/DECstation URLs.

Applying a patch from Andreas Gustafsson (gson) for the MIPS div and ddiv instructions, which checks for divide overflow manually before doing the divide.

Updating HelenOS from 0.7.1 to 0.7.2.

Adding another VoCore linux kernel example.

Adding comment about FreeBSD/VoCore kernel testing.

Fake MIPS 24KEc model, used by VoCore.

Adding a minimal VoCore palmbus skeleton, enough to print boot messages.

Minor progress on booting Linux/VoCore. MIPS rdhwr CC is implemented as reading the COP0_COUNT register.