Changing an ASCII character operand back to default was going
through a path that tried to resolve low vs. high ASCII, which
isn't useful when you're removing the item. The root of the problem
was that the "default" button wasn't properly resetting the UI.
Also, updated keyboard shortcuts to be in sync with the instruction
operand editor.
I ran into a non-split table of 16-bit addresses, each of which
was (address-1) for a code location. I wanted to create a label,
add a code hint, and set the operand for each one, but there's no
easy way to do that.
It turns out the split-address table formatter can be made to work
for non-split tables with just a few minor changes.
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.
