Nette 2.0.3

Added option to set custom marker image.

Use
===

```
$gmaps = new \Gmaps\Gmaps;
$gmaps->addMarker($name, $destination, $title, $info, new \Gmaps\MarkerImage(
  $url = '/images/marker.png', 
  $size = array(50,50), 
  $origin = array(0,0), 
  $tip = (25,50)
);
```