ol-ext: Overview map control
create an overview similar to the ol.control.overview
The main differences is that you can limit the zoom level on the overview and force the overview to be oriented north.
Limiting the min zoom of the overview will magnify the map.
Limiting the max zoom avoid to zoom in the overview and draw the position as a point on it when extent is too small.
You can use the style option to choose the style of the box drawn on the overview.
If the box is too small a point will be drawn instead (ol.style.Image of the style).
Click on the overview map to move the center of the map to that point.
option move the map with an elastic animation.