function previousImage() {
    var elt = $('div.navigation>a.previous');
    if (elt.length == 1) document.location.href = elt.attr ('href');
    else if ($('div.navigation>a.reload').length == 1) document.location.reload();
}

function nextImage() {
    var elt = $('div.navigation>a.next');
    if (elt.length == 1) document.location.href = elt.attr ('href');
    else if ($('div.navigation>a.reload').length == 1) document.location.reload();
}


function beginNavigationByKey () {
    $(document).bindkey('left', previousImage);
    $(document).bindkey('right', nextImage);
}