Squashed commit of the following:

commit d00623d60afd460755b749ad5f94935f756f29d2
Author: musitdev <philippe.delrieu@free.fr>
Date:   Sat Jan 4 22:31:40 2014 +0100

    correct last comments.

commit ef09d6b6d1eebbd7c713c9dad96ed7bfc19dd884
Author: musitdev <philippe.delrieu@free.fr>
Date:   Thu Jan 2 20:28:53 2014 +0100

    update with the last remarks.

commit 46a028fe1fcdc2a7dcdd78a63001793eff614349
Author: musitdev <philippe.delrieu@free.fr>
Date:   Thu Jan 2 10:17:18 2014 +0100

    wrap example code in main function.

commit 2472901929bef09786b7aef8ca7c89fbe67d8e3e
Author: musitdev <philippe.delrieu@free.fr>
Date:   Mon Dec 30 19:32:46 2013 +0100

    Correct code to compile.

commit ed96b2223176781743e984af0e19abcb82150f1f
Author: musitdev <philippe.delrieu@free.fr>
Date:   Thu Dec 5 11:32:28 2013 +0100

    Correct the comment based on the PR comment.
    Change init call to new to reflect last change.

commit 38b0390c3533a16f822a6df5f90b907bd8ed6edc
Author: musitdev <philippe.delrieu@free.fr>
Date:   Wed Dec 4 22:34:25 2013 +0100

    correct from_utf8_owned call.

commit 08bed4c5f4fadf93ec457b605a1a1354323d2f5c
Author: musitdev <philippe.delrieu@free.fr>
Date:   Wed Dec 4 22:12:41 2013 +0100

    correct code '''

commit 02fddcbe2ab37fe842872691105bc4c5cff5abb5
Author: musitdev <philippe.delrieu@free.fr>
Date:   Wed Dec 4 13:25:54 2013 +0100

    correct typing error

commit b26830b8ddb49f551699e791832ed20640a0fafc
Author: musitdev <philippe.delrieu@free.fr>
Date:   Wed Dec 4 13:18:39 2013 +0100

    pass make check

commit e87c4f53286122efd0d2364ea45600d4fa4d5744
Author: musitdev <philippe.delrieu@free.fr>
Date:   Wed Dec 4 10:47:24 2013 +0100

    Add Json example and documentation.
Correct MemWriter inner call to unwrap.
auto merge of #10801 : musitdev/rust/jsondoc2, r=cmr

I update the example of json use to the last update of the json.rs code. I delete the old branch.
From my last request, I remove the example3 because it doesn't compile. I don't understand why and I don't have the time now to investigate.