Add alternate colors for each color.

[janxious]

• This adds the original color, then the extras.
• Keybind (rebindable, default i) to rotate your colorset to the next color in the list
• Allow for varied list sizes (but remember we move all slots at once)

[janxious]

In order to enable some other stuff, I think I'm going to change the default setting format to:

    "colorToggleKeys": ["shift", "i"],

    "direct": {
      "active": true,
      "colors": [[0, 255, 128, 255]],
      "dashed": true,
      "thickness": 1
    },
    "indirect": {
      "active": true,
      "colors": [[255, 128, 0, 255]],
      "dashed": true,
      "thickness": 1.75
    },
    "obstructedAttackerSide":  {
      "active": true,
      "colors": [[0, 64, 255, 255]],
      "dashed": true,
      "thickness": 1
    },
    "obstructedTargetSide":  {
      "active": true,
      "colors": [[153, 0, 255, 230]],
      "dashed": true,
      "thickness": 1.25
    }

That implies a lot of semi-new features in addition to the color toggling. But it means no special cases.