Dark mode color scheme

[uxmal]

Let's discuss the color scheme for dark mode in the upcoming Avalonia port. Here's my first stab, but it really needs improvement:

I've attached a simple HTML document to tinker with here. Github won't let me add it as HTML, so I've renamed the file extension
prototype.html.txt

[uxmal]

Note the slight tone change in the mnemonic column; slightly different shades of red to indicate the different instruction classes. Blueish for clickable things, greenish for comments. The default gray color is hopefully not too bright.