Interactive map update

We've updated the interactive map:

• completely redesigned the look and feel;
• added a grid;
• added the ability to draw directly on the map;
• added the ability to export the map, including all added content, as a PNG;
• added the ability to share a link to a specific marker; selected marker states are now preserved after refreshing the page;
• implemented a range of optimizations to improve the map's performance.