BUG: non-fixed-length ISAs are unsupported for now

[Frank Ch. Eigler]

Hi -

> Ok. How to handle variable size instructions then? For example:
> NOP - 0x00
> NEG - 0xed 0x44
> RLC B - 0xcb 0x00
> LD HL, 0x1234 - 0x21 0x34 0x12
> LD IY, 0x1234 - 0xfd 0x21 0x34 0x12
> LD DE, (0x1234) - 0xed 0x5b 0x34 0x12
> RR (IX+9) - 0xdd 0xcb 0x09 0x1e (here 0x09 is 8-bit signed immediate)

Simply, make no change other than setting the base-insn large enough
to contain all the opcode fields.  Amongst all these cases, that seems
to be 16 or perhaps 24 bits.  I suggest trying 32.

- FChE