Support cool-retro-term themes

[pbnj]

cool-retro-term is a retro terminal emulator.

It supports custom themes via JSON files, like so:

{
  "backgroundColor": "#020000",
  "fontColor": "#5efaac",
  "flickering": 0.2015,
  "horizontalSync": 0.1072,
  "staticNoise": 0.1004,
  "chromaColor": 0.2486,
  "saturationColor": 0.4012,
  "screenCurvature": 0.5,
  "glowingLine": 0.0286,
  "burnIn": 0.0982,
  "bloom": 0.5,
  "rasterization": 0,
  "jitter": 0.2464,
  "rbgShift": 0.0522,
  "brightness": 0.5,
  "contrast": 0.85,
  "ambientLight": 0.0309,
  "windowOpacity": 1,
  "fontName": "System: Nimbus Mono PS",
  "fontWidth": 1,
  "margin": 0.5,
  "name": "The Matrix has you...",
  "version": 2
}

Many of these properties (e.g. jitter, ambientLight, rasterization, bloom, burnIn, ...etc) are likely not relevant and could possibly be left out. The ones that are relevant are backgroundColor, fontColor, and name, which makes it relatively easy to support.

More example themes can be found here: https://github.com/Swordfish90/cool-retro-term/wiki/Third-Party-Themes

[jdhmtl]

At a glance, it appears to cool-retro-term seeks to emulate the look and feel of old monochrome displays. Do colour schemes even make sense in that context? Certainly, you'd lose nearly all the colours.