Debugger improvements

[parasyte]

Followup to #5, these improvements are to the r4300i Commands window. Primary changes:

• Added selection and CTRL+C to copy lines.
  • Supports selection ranges larger than the ListView; scroll and Shift+Click to select all text from the anchor to the click location (even across multiple pages).
  • Scroll-on-select would be nice to have, but it is not implemented here.
  • Keyboard selection would also be nice. Shift + arrows/page up/page down seems like it would be a decent UX... TBD.
  • Right click to copy + deselect. Or hold left click and press Esc or right click to deselect without copying.
• Added support for scrolling with the mouse wheel.
• Added support for scrolling with the keyboard when the ListView has focus.
• Added support for scrolling with the scrollbar thumb.
• Switched to a fixed-width font for better readability.
• Show opcodes (instruction bytes).
• Increased the window size to accommodate the better font and OpCode column.
• Normalized all instructions to lowercase.
• New colors to represent instruction state:
  • Red: Breakpoint
  • Green + outline: Current PC
  • Orange + outline: Current PC + breakpoint
  • Blue background: Selection highlight
• Fix watchpoint access size checks so they don't have to be an exact match on the address.
• Minor bug fixes.

Some additional things I would like to do before merging:

• [x] Show instruction opcodes (bytes)
• [x] Copy to clipboard
• [ ] ~Inline assembler~ (postponed)

Copying requires either selecting a range of lines or just always copy whatever is drawn to the screen. I would like to make it possible to select ranges larger than what can be shown in a single page. It's a bit of work.

The inline assembler would allow editing instructions. It could also make use of the line range selections.

[parasyte]

This PR is big enough already. I'll do the inline assembler in another pass. For now, this is ready for wider testing. I'll squash and merge in a day or two if I don't hear any feedback suggesting against it.

[oddMLan]

All LGTM, the only suggestions I would have is to make the Memory viewer able to copy/paste but I know making it a full-fledged Memory Editor is in the plans. Other than that, maybe I would add access to the memory/binary dump not just from the Cheat search but the Debugger menu as well, maybe inside the memory viewer window, seems more logical that way.

[parasyte]

Thanks @oddMLan. Those all sound like good things to include! Selection and clipboard support for the memory viewer is coming in another PR. I can add access to the dump dialog there too.

Editing memory is also in the game plan.