Resolves #104 and #105

[blackboxlogic]

#105

Removing multiple markers only removes 1.

[blackboxlogic]

Also fixing an issue where using UpdateHtmlMarkersAsync didn't update the options in c# memory, so updating an option then getting the value of the option gave the old value. Consider:

	public async Task OnMapClick(MapMouseEventArgs eventArgs)
	{
		var options = new AzureMapsControl.Components.Markers.HtmlMarkerOptions { Visible = !Marker.Options.Visible };

		await eventArgs.Map.UpdateHtmlMarkersAsync(new AzureMapsControl.Components.Markers.HtmlMarkerUpdate(Marker, options));
	}

[blackboxlogic]

@arnaudleclerc It seems like this repo might not be actively maintained? If that's the case, it might be nice to put that first thing in the README so people know what to expect.

[arnaudleclerc]

Sorry for the delay @blackboxlogic ! I am not as active anymore on this project as I would like to be.

Your changes look good, thanks for taking care of it.

[blackboxlogic]

Thank you! It seems like this got released as 1.17.0