Add a `*` option to `nodeExtra`

[kirangadhave]

Currently we have to specify an element for each event type innodeExtra. We should have a catch all key * which adds the element to every node. Something like:

{
    nodeExtra: {
        '*': <div>Will show for all</div>
    }
}

We can fix this so that it is rendered before an event specific nodeExtra value.