Support more palette formats

[Rangi42]

• [x] JSON (same schema as supefamiconv)
• [x] paint.net (TXT)
• [x] Adobe Photoshop Color Swatch (ACO)
• [x] Adobe Swatch Exchange (ASE) (see also)
• [x] CorelDraw (XML)
• [x] Fractint (MAP)
• [x] Hex (same format as Lospec or Cyotek Color Palette Editor)