Add option to collapse groups

Dear contributors,

I would find nice to implement some sort of collapsing of the groups. Here is how I did it quick and dirty with jqm :

if (!groupContainer) {
    [...]

    groupLabel.innerHTML = obj.group.name + "<span class='group-button' id='layers-group-"+obj.group.id+"'>&nbsp-</span>";

    container.appendChild(groupLabel);
    container.appendChild(groupContainer);

    [...]
}

At the end, added :

$('body').delegate('.group-button', 'click', function()
{
    var myid = $(this)[0].id
    console.log(myid)
    if ($("#"+myid).html() == " +")
    {
        $("#leaflet-control-"+myid).children().show()
        $("#"+myid).html(" -")
    }
    else
    {
        $("#leaflet-control-"+myid).children().hide()
        $("#"+myid).html(" +")
    }
})

Best regards,

[tsrman]

Im litte bit busy for this time, i try create pull request on next week.

[hjrobinson]

Okay, so I used the fork, but the only way I can add polygons to the layer control (and avoiding a failed page load) is by extracting coordinates from a geoJSON file and adding them to into a polygon. I guess I could try to write a loop to convert the text, but is there a way to get L.geoJSON directly into the layer instead of using L.polygon?