Feature Request: support real time data

[baoqger]

Please take a look up my description in this post: https://stackoverflow.com/questions/57752432/leaflet-markcluster-clean-and-add-markers-dynamically-with-real-time-data

Simply speaking, use clearLayers() and add markers again will have issue about the spiderfied cluster

[BenTalagan]

Hi, the real time updates affecting the spiderfy behavior issue has been referenced multiple times but IIRC it's not been fixed yet. There's a PR about it that was not merged and has been closed for inactivity #435, maybe if you feel skilled enough, you could try to make it work again and complete it?