Fix for a version where the map was getting stuck on initialisation
sometimes...
Reusing the map markers rather than re-creating each time...
Making markers clickable if they have a relevant link...
When you roll over a marker the corresponding list item is highlighted
Making it so that the marker icons change colour when you roll over
them...
...and rolling over a row in the list makes the corresponding icon
change colour...
Added tooltips to the icons on the side map...