r7695 /src/emu/cpu/g65816/ (g65816.c g65816op.h): Added boundary checks for MVN and MVP opcodes in the G65816 CPU core, fixes booting in Iso Zuri Ritou Hen

In M mode, game does the following:

A = 0x10
B = 0x01

... when it transitions from 0x100 to 0xff, A had an identity crisis and suddently believes to be a 32-bit CPU register, hence it becomes 0xffffffff, cause of the crash. I've forced that to mask with 0xff to avoid it.

And now, some nice images of this *awesome* game wink