Housekeeping

[rod-glover]

The code can be considerably cleaned up and improved, making maintenance easier. Major things to do:

• [x] Move all process.env into configuration.js
• [x] Move all initialization into a separate module; invoke in index.js or App.js
• [x] Configure map spinner from env vars: JSON
• [x] Make config more robust to bad JSON, others?
• [x] Move dataDownloadUrl from Body to util
• [x] Place stnsLimitOptions in config (Body.js:52)
• [x] Place defaultLgs in config (Body:49)
• [x] Move metadata (and fetching) into a hook.
• [x] Remove marker clustering
• [x] Move import of leaflet styles to index.js. (no: imported by pcic-react-leaflet-components)
• [x] Clean up errors/warnings showing in console
• [x] Consider whether other configs could be with JSON
• [x] extract tabs to separate components?
• [x] Update dev documentation.

[rod-glover]

James looked over demo deploy and approved.