nex protocol handler

[hachiya-kurisu]

Not sure how this is done implementation-wise, but (at least on os x) Lagrange doesn't seem to register a nex:// protocol handler. gemini:// and spartan:// links all open in Lagrange, but I have to copy/paste nex:// links 🤔

[skyjake]

The handlers are registered in the application's .plist file. I'll need to add Nex there.