During a discussion with the cc65 developers, I became convinced that
generating "MVN $01,$02" is wrong, and "MVN #$01,#$02" is correct.
64tass, cc65, and Merlin 32 all accept this syntax; only ACME does
not. Operands without a leading '#' should be treated as 24-bit
values, and have the bank byte extracted.
This change updates the on-screen display and assembled output to
include the '#'. The ACME generator uses a Quirk to suppress the
hash mark. (It doesn't currently accept values larger than 8 bits,
so there's no ambiguity.)
The 65816 definition makes it a two-byte instruction, like COP. On
the 6502 it acted like a two-byte instruction, but in practice very
few assemblers treat it that way. Very few humans, for that matter.
So it's now treated as a single byte instruction, with the following
byte encoded as a data value.
