Functions to understand or clarify, related to displaying scores and messages :

checkAnswerChanged: called on a regular basis to check if the message needs to be updated because the user has changed his current answer
restartAll: called when we click on "restart all" button
validate: called by the platform after a call to platform.validate, or if we validate while the solution is visible. sometimes called by tasks, but shouldn't be
updateScore: recalculate and display the scores for a given answer, and either for the current level or all levels
updateScoreOneLevel: same but for a given level (this is where gradeTask is called, from the task's side)
updateScoreDisplays: update the display of scores in tabs (and at the bottom of the task?)
hasNonSavedAnswer: do we have an answer that is different from the default answer, that has not been submitted yet?
retreiveAnswer (to fix)
reloadAnswer
reloadState


- why do you need to go through the platform to validate an answer? Shouldn't buttonsAndMessages determine whether the new answer is better than the previous one, and only
transfer to the platform if it was better ? => Not necessarily. We could allow the platform to record every attempt. It's for the platform to decide.

Study of the most important variables:

- savedAnswer:
=> Corresponds to the best answer so far, the one we provide to the platform.
   - reset to '' when cancel is called (never used on new tasks, this is for multiple choice etc.)
   - if we validate :
	- recorded if we are not in fullback (showScore) mode
	- otherwise
		- if there are no levels: recorded if the score is better than before
		- if there are levels: we record the score of the current level if it is better than before
   - reset to the given value if reloadAnswer is called (a little surprising. What if we had a better answer saved ?

- sumbittedAnswer:
=> Corresponds to the answer which score should be displayed, if there is one (current answer validated, and not modified since then)
   - reset to the answer given, if we call reloadAnswer
   - reset to savedAnswer's value if we call retreiveAnswer
   - set to the answer given, if we call validate
   - reset to '' as soon as the current answe is different from this answer

- graderScore :
=> Corresponds to the score of the best answer (for the current level)
   Question: is this correctly updated when we change level ?
   - initialised to "noScore" in load
   - if we are in solution mode, set to the value provided by the grader in updateScoreOneLevel
   - set to the new value if it is better, when calling gradeTask from updateScoreOneLevel

- levelsScore :
=> Corresponds to the score of the best answer for each level
   - if we are in solution mode, this is the value, for the current level, just like gradeAnswer
   - set to the new value if it is better (for the current level), when calling gradeTask

- prevLevelsScores
=> Corresponds to the best score we had just before validating (using levels)
   - when we just validated, set to the current value of levelsScores

- prevSavedScore
=> Corresponds to the best score we had just before validating (no levels)
   - in showView, if we show the solution and graderScore is defined, we set it to this value
   - when we just validated, set to the current value of graderScore

- prevAnswer
=> This is just the answer as it was the last time we looked
   - reset to the value provided, when calling reloadAnswer
   - set to the current value of answer, every time hasNonSavedAnswer is set

- defaultAnswer
=> Corresponds to the value of getAnswer() when nothing has changed since the task was loaded
   - set to the current answer provided by getAnswer, when calling showViews (done right after load, so after getDefaultAnswerObject, if there are levels)

- hasAnswerChanged
=> Just saves the fact the the answer has just changed compared to last time we checked
   - true at the beginning
   - set to true in checkAnswerChanged if hasNonSavedAnswer says true
   - set to false in checkAnswerChanged if hasNonSavedAnswer says false(?)

- refreshMessages
=> Indicates that it is necessary to update messages
   - set to true when showView is called
   - set to true when retrieveAnswer is called
   - set to true when setLevel is called
   - set to true in checkAnswerChanged if submittedAnswer is not empty
   - set to true if we have just changed hasAnswerChanged
   - set to false when updateMessages is called

- stoppedShowingResult
=> Indicates if it is still necessary to display the result at the bottom of the page (grader's message)
   - set to true when stopShowingResult() is called
   - set to false when validate is called


- previousMessages
=> stores the previous message, to determine if it is useful to redisplay the new message (avoided some blinking in the past, not sure if still necessary, I think there was a better fix done recently)
    - set to the value of messages, right after they are displayed in updateMessages

- submittedScore
=> Corresponds to the score of the answer we just validated, or of the best answer if we just changed level
    - set to the best score for the current level when we change level
    - set to the new score when we just called the grader