TODO

   1 Replace underscore by lodash (or better: ES6)
   2 Replace socket.io by Websockets ( https://www.npmjs.com/package/websocket )
   3
   4 time per question (in mode "one question at a time" from server...)
   5 compute grades after exam (in teacher's view)
   6 factorize redundant code in course.js, monitor.js and (TOWRITE) grade.js
   7   (showing students list + grades or papers)
   8
   9 -----
  10
  11 TODO: format général TXT: (compilé en JSON)
  12
  13 10 (time)
  14 1 (fixed)
  15 Introduction (multiline, from third line ; \n --> <br>)
  16
  17 [Intro q1, multiline]
  18
  19 q1 txt
  20
  21 answer q1 (multiline txt)
  22
  23 q2 intro (multiline)
  24
  25   q2.1 [intro optional]
  26
  27     q2.1 txt
  28
  29     q2.1 options:
  30     + good
  31     - bad
  32     - bad ...etc
  33
  34     answer (integer array, one line)
  35
  36   q2.2 [intro optional]
  37
  38     q2.2 txt
  39
  40     answer (html multiline)
  41
  42 Conclusion (last block)
  43
  44 =====
  45
  46 Seems that GUI would be easier, then summary in YAML file + parse from YAML