message: [terminal] Color: stringification of RGBColor hould be `#RRGGBB` instead of `0xRRGGBB`.
  Because a VIM plugin can easily colorize the former but not the latter.
diff: @@ -90,8 +90,8 @@ RGBColor& RGBColor::operator=(string const& _hexCode)
  string to_string(RGBColor const c)
  {
  - char buf[9];
  - auto n = snprintf(buf, sizeof(buf), "0x%02X%02X%02X", c.red, c.green, c.blue);
  + char buf[8];
  + auto n = snprintf(buf, sizeof(buf), "#%02X%02X%02X", c.red, c.green, c.blue);
  return string(buf, n);
  }
  