The disassembler now accepts a range of start addresses and remembers
old entry points, so the disassembly becomes more complete each time
the debugger is used.

Changes to address offsets within the same bank are now supported
(ie, changing from $fxxx to $dxxx within the same bank properly
updates the display).

Re-added ability to manually change banks from the debugger prompt
and the disassembly UI.  This now works correctly with the Distella
code.

Cleanup of the Cartridge::bank(...) API: if a bank cannot be changed,
the calling code will now know about it.  This fixes confusion with
some ROMs, whereby changing a bank in the debugger prompt would print
a success message even if the operation failed.

Note that these changes have broken rewind in the debugger.  Actually,
it only exposes problems that the rewind functionality already had :)


git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2098 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba