Unable to find multiple paths with same startNode

At the moment the grid is unable to re-use the start node for multiple paths. My assumption is because the startNode gets a 'closed state'

The workaround is : `finder.findPath(x0, y0, x1, y1, this._grid.clone())`

but cloning doesn't seem to be very performant when having to find multiple paths. Any way that this could be optimized/looked at?