Bug when using map option `preferCanvas: true` (canvas renderer for paths) and removing then adding back a vector within the same animation frame (typically in the same sequence, as done by Leaflet.markercluster at `"zoomend"` event, to remove layers and clusters outside visible bounds).
This commit clears the `_removed` flag from paths when they are added to the canvas.
Also added corresponding test suites.
- fix fireEvent called for each layer containing event point
- fix layer not removed from this._layer at remove
- fix L.DomEvent.stop(e) not honoured for canvas because events
are both listenned on canvas container and map container
