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.
Instead of providing no-op CheckJsr/CheckJsl, plugins now declare
which calls they support by defining interfaces on the plugin class.
I added a CheckBrk call for code like Apple /// SOS calls, which
use BRK as an OS call mechanism. The formatting doesn't work quite
right yet because I've been treating BRK as a two-byte instruction.
Hardly anything else does, and I think it's time I stopped (but not
in this commit).
Note: THIS BREAKS ALL PLUGINS that use the inline JSR/JSL feature,
which is pretty much all of them.
In the cross-reference table we now indicate whether the reference
source is doing a read, write, read-modify-write, branch, subroutine
call, is just referencing the address, or is part of the data.
