Possibility to refuse to answer

[Nicolas Aillery]

Addition of the possibility to explicitly refuse to answer:

-
+
<section anchor="explicitly_refuse" title='Allowing the user to explicitly refuse to answer'>

    <t>
    The user MAY refuse to answer. To do so, the user can ignore the question and wait for the timeout.  
    In order to offer a better experience, it is RECOMMENDED that the OP gives the user the opportunity to explicit state this refusal.
    A "user_refused_to_answer" error is then returned. 
    </t>

</section>

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[Bjorn Hjelm]

Approved.