Refactor handling of click handler

Refactor click handlers and remove superfluous arguments to click handlers.
This will help merge the Iceland version of googleMaps.js with that in Scripts.
Refactor onload and onunload for maps
Use shared googleMaps.js for Iceland
Fix a load of style
Make passing shadow image optional

No functional change
Update to use Maps v3 API

Note that this requires a switch to the HTML5 doctype.