Prepare for additional pages with maps

Fixes #483.
I'm confused by this.
Why can you just instantiate this, without `mapManager.createTreeMap` like `map.js` and `mapFeature.js` do?

Do the `MapManager` methods called in `searchBar.js` not required the map to be initialized?
If so, I don't think you should have to instantiate the an object to use what are essentially "static" methods.

If this is the case, could those specific methods be moved to a different module?