JSON output support for `fmap usage`

[orangecms]

That would be great to have for further processing and visualization. It could look like this (just some edited output); excerpt:

{
  "Legend": "'.' - full (0xff), '0' - zero (0x00), '#' - mixed",
  "data": {
    "0x00000000": "................................",
    "0x00020000": "####################...#........",
    "0x00040000": "......................#.........",
    "0x00060000": "................................",
    "0x00080000": "................................",
    "0x000a0000": ".......###########......########",
    "0x000c0000": "################################"
  },
  "Blocks": "4096 (100.0%)",
  "Full (0xff)": "1695 (41.4%)",
  "Empty (0x00)": "30 (0.7%)",
  "Mixed": "2371 (57.9%)"
}

Another option would be to have full data structures that require no further parsing and can be used as-is.