Redrawing icons does not redraw icons in spiderfied view

[sibbl]

In contrast to the original Leaflet.markercluster plugin, neither the forceIconRedraw = true nor the RedrawIcons approach call the update functions of the markers in the spiderfied view.

So currently the markers are not updated when they're in a spiderfied cluster when e.g. new data arrives although they should.

[fungiboletus]

The spiderfied view is not dynamic. It's the same problem than #124

[cordovapolymer]

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