Marking places on the map

Hello,

I put my code for displaying marks into MapPanel.

`com.roots.map.overlay.OverlayDemo` contains a sample of how to display red dots over Artyom and Cologne.

![mappanel_2013-10-14_01-19-02](https://f.cloud.github.com/assets/1143055/1322812/439d0d56-344d-11e3-8d4a-10bf63638fef.png)