This is the first step toward changing the address region map from a
linear list to a hierarchy. See issue #107 for the plan.
The AddressMap class has been rewritten to support the new approach.
The rest of the project has been updated to conform to the new API,
but feature-wise is unchanged. While the map class supports
nested regions with explicit lengths, the rest of the application
still assumes a series of non-overlapping regions with "floating"
lengths.
The Set Address dialog is currently non-functional.
All of the output for cc65 changed because generation of segment
comments has been removed. Some of the output for ACME changed as
well, because we no longer follow "* = addr" with a redundant
pseudopc statement. ACME and 65tass have similar approaches to
placing things in memory, and so now have similar implementations.
My original goal was to add a sign-extended decimal format, but that
turned out to be awkward. It works for data items and instructions
with immediate operands (e.g. "LDA #-1"), but is either wrong or
useless for address operands, since most assemblers treat integers
as 32-bit values. (LDA -1 is not LDA $FFFF, it's LDA $FFFFFFFF,
which is not useful unless your asm is doing an implicit mod.)
There's also a bit of variability in how assemblers treat negative
values, so I'm shelving the idea for now. I'm keeping the updated
tests, which are now split into 6502 / 65816 parts.
Also, updated the formatter to output all decimal values as unsigned.
Most assemblers were fine with negative values, but 64tass .dword
insists on positive. Rather than make the opcode conditional on the
value's range, we now just always output unsigned decimal, which
all current assemblers accept.
