title: Write / change raw ID3 tags?
body: <p>I have an MP3 file: </p>
  
  <pre><code>B{
      255 251 144 100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
      0 0 0 0 0 0 0 0 0 0 0 0 0 0 73 110 102 111 0 0 0 15
      0 0 30 161 0 50 3 66 0 3 5 8 10 13 15 18 20 24 26 28
      31 33 36 38 41 43 47 49 52 54 56 59 61 64 66 69 72
      75 77 79 82 84 87 89 92 95 98 100 103 105 107 110
      112 115 118 ~3277535 more~
  }
  </code></pre>
  
  <p>And I have some metadata I want to put in it:</p>
  
  <pre><code>H{
      { "title" "Superstar (feat. Krewella)" }
      { "artist" "Pegboard Nerds &amp; NGHTMRE" }
      { "num" 1 }
  }
  </code></pre>
  
  <p>Factor doesn't have a vocabulary to write ID3 tags (yet), but I have the raw file data and some data I'd like to write. </p>
  
  <p><a href="https://en.wikipedia.org/wiki/ID3#ID3v2" rel="nofollow">Wikipedia</a> isn't any help, and the <a href="https://www.mpg123.de/api/mpg123_8h_source.shtml#l01162" rel="nofollow">mpg123</a> source doesn't really clear anything up either. </p>
  
  <p>How do I put the data from the hashtable into the ID3v2 header?</p>