Auto-reload, Open links, Proxy

• Auto-reload on file save (both for HTML as associated local JSON-LD files)
• Double-click on id-value in subject, predicate, object pane will attempt to open that URI in a browser.
• Clearer error messages when failing to load a file.
• Clearer info message when loading data from external locations (including count of triples added)
• Basic Python proxy code in Flask, useful to circumvent CORS and/or redirect to APIs.
• CSS tweaks