2009-07-17 Flatmap Viewer version 0.7.4

This update:

• improves the display of background layers.
• shows a progress cursor during edge and node queries.
• standardises data sent by the message channel.
• provides a method, getIdentifier(), to return an object to identify a map.
• Besides a text string to identify a map, loadMap() will also accept a getIdentifier() object.
• provides a method, getState(), to return an object containing a map's current state (its centre, zoom level, and active layers).
• adds a state field to the options parameter of loadMap() to load a map and restore it to a previously saved state.
• adds a setState(state) method to restore a map to a previously saved state.
• returns a Promise from loadMap() that is resolved when the map is loaded.