This involved adding a list to the DisasmProject, creating a new
UndoableChange type, and writing the project file serialization
code. While doing the latter I realized that the new Width field
was redundant with the FormatDescriptor Length field, and removed it.
I added a placeholder line type, but we're not yet showing the
table in the display list. (To edit the tables you just have to
know where they are.)
The table editor is now editing the table, and the DefSymbol editor
now asks for the Width data when editing a local var.
This also moves EditDefSymbol closer to proper WPF style, with
bound properties for the input fields.
No changes yet to serialization or analysis.
Both dialogs got a couple extra radio buttons for selection of
single character operands. The data operand editor got a combo box
that lets you specify how it scans for viable strings.
Various string scanning methods were made more generic. This got a
little strange with auto-detection of low/high ASCII, but that was
mostly a matter of keeping the previous code around as a special
case.
Made C64 Screen Code DCI strings a thing that works.
It's not quite the same as the character encoding -- sometimes we
want a mix of things -- so it gets its own enum. The value is
saved to the project file, but not actually used yet.
Also, moved some combo box strings into XAML resources.
