Implemented assembly source generation of non-unique local labels.
The new 2023-non-unique-labels test exercises various edge cases
(though we're still missing local variable interaction).
The format of uniquified labels changed slightly, so the expected
output of 2012-label-localizer needed to be updated.
This changes the "no opcode mnemonics" and "mask leading underscores"
functions into integrated parts of the label localization process.
In a recent survey, three out of four cross assemblers surveyed
recommended not using opcode mnemonics to their patients who use
labels. We now remap labels like "AND" and "jmp", using the label
map that's part of the label localizer.
We skip the step for Merlin 32, which is perfectly happy to assemble
"JMP JMP JMP".
Also, fixed a bug in MaskLeadingUnderscores that could hang the
source generator thread.
There's no easy way to make non-zero-bank 65816 code work, so I'm
punting and just generating a whole-file hex dump for those. This
renders tests 2007 and 2009 useless, so I'm hesitant to claim that
ACME support is fully functional.
