Add layout editing

[jonko0493]

Being able to edit system textures is all fine and good, but we know for a fact that many of those textures are actually mapped onto the screen with layouts. The translation utility has some ability to edit these layouts, but we should implement a better version of that here.

This will likely require a lot of hardcoding stuff (as indeed, most of the layout interactions are hardcoded), but I think that's probably fine.

[jonko0493]

Moving this up to v0.3 milestone as a cross-plat version of what the utility can do is needed for some of the translation work.