96/08/21

I've added all the opcodes, except for the ill-defined "SET" and "TST"
opcodes which appear in multiple places.

FEATURES:
---------
Well, I didn't implement these in a big way...

At Command-line, 'b' sets a breakpoint (only 1 available).
Enter 4 Hex digits (they unfortunately won't be echoed to the screen).

At Command-line, 'g' sets the simulator running full speed until a
non-executable instruction or the breakpoint is hit.

Of course, 'x' executes the single instruction, and 's' skips it.
'z' = view zero page.

Hopefully soon to come are zero-page and general memory view/modify,
and register modify operations.  And hopefully a clean-up of the
existing ones.
