Line length should not be longer than 75 characters about ics

[ryanwitt]

I recall running into problems with outlook for .ics files that don't follow this spec.

Found the following code in my custom .ics generator, where @line needs to be the entire line, including the LABEL:

  function foldLine (line) {
    const parts = []
    while (line.length > 75) {
      parts.push(line.slice(0, 75))
      line = line.slice(75)
    }
    parts.push(line)
    return parts.join('\r\n\t')
  }

I'm considering a PR, but am looking into other changes needed for my use case first.

edit: I think it's more correct to ensure that the tab character counts toward the 75-character limit

function foldLine (line) {
  const parts = []
  let length = 75
  while (line.length > length) {
    parts.push(line.slice(0, length))
    line = line.slice(length)
    length = 74
  }
  parts.push(line)
  return parts.join('\r\n\t')
}

[ryanwitt]

Meanwhile @wadouk, I think you could use the above function on the input if you added, then subtracted the label first, i.e.

const event = {
  ...
  description: foldLine('DESCRIPTION: ' + longLine).slice('DESCRIPTION: '.length),
  ...
}

[adamgibbons]

Closed by #66 (thanks again @ryanwitt).