Loading speed was very slow because the JSON for locations took time to generate, so I've moved that process offline; it now runs as part of the utilities/createGazetteer.xsl file, and generates two new JSON files (one for categories, one for locations) in the db/generated folder. That speeds everything up.

I now have the GUI for locations and categories working as I want it to, so that checking and unchecking both categories and locations is coordinated and shows the proper state to the user. Next step is converting coords to proper feature coords for OpenLayers.