GXemul Code2

Attempting to begin to convert the ISA bus.

Beginning on the new interrupt subsystem.

Implementing some parts of the Dreamcast GDROM device, and various other SH4 and Dreamcast-related updates.

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Dreamcast updates.

Continuing on SH4 and Dreamcast stuff. Adding a bogus Landisk (SH4) machine mode.

CCC compiler warnings fixes

Adding a -T command line option (again?), for halting the emulator on unimplemented memory accesses.

Adding a new disk image option (-d o...) which sets the ISO9660 filesystem base offset; also making some other hacks to allow NetBSD/dreamcast and homebrew demos/games to boot directly from a filesystem image. Adding a border to the Dreamcast PVR framebuffer.

Moving Dreamcast-specific stuff in the documentation to its own page (dreamcast.html).