byuu says:

Changelog:

  - Interface::displays() -> vector<Display> → Interface::display() -> Display
  - <Platform::videoRefresh(display>, ...) → <Platform::videoFrame>(...)
  - <Platform::audioSample>(...) → <Platform::audioFrame>(...)
  - higan, icarus: use AboutDialog class instead of ad-hoc
    implementations
      - about dialog is now modal, but now has a clickable website URL
  - icarus: reverted if constexpr for now
  - MSX: implemented basic CPU, VDP support

I took out the multiple displays support thing because it was never
really implemented fully (Emulator::Video and the GUIs both ignored it)
or used anyway. If it ends up necessary in the future, I'll worry about
it then.

There's enough MSX emulation now to run Mr. Do! without sound or input.
I'm shipping higan with C-BIOS 0.29a, although it likely won't be good
enough in the future (eg it can't do BASIC, floppy disk, or cassette
loading.) I have keyboard and (not working) AY-3-8910 support in a
different branch, so that won't take too long to implement. Main problem
is naming all the darned keyboard keys. I think I need to change
settings.bml's input mapping lines so that the key names are values
instead of node names, so that any characters can appear inside of them.

It turns out my MSX set uses .rom for the file extensions ... gods. So,
icarus can't really import them like this. I may have to re-design
icarus' importer to stop caring about the file extension and instead ask
you what kind of games you are importing. There's no way icarus can
heuristically guess what systems the images belong to, because many
systems don't have any standardized magic bytes.

I'm struggling with where to put SG-1000, SC-3000, ColecoVision, Coleco
Adam stuff. I think they need to be split to two separate higan
subfolders (sg and cv, most likely ...) The MS/GG share a very
customized and extended VDP that the other systems don't have. The Sega
and Coleco older hardware share the same TMS9918 as the MSX, yet have
very different memory maps and peripherals that I don't want to mix
together. Especially if we start getting into the computer-variants
more.