Generate port settings in ports

[kripken]

Instead of a port having to modify settings.js, give them a hook to
add new settings.

See discussion in #11066

[sbc100]

Hmm.. I think I like this approach. I was going to suggest an alternative approach, which I think maybe we should still take in addition to this.

We have a single setting called USE_PORT=foo which triggers the loading and activation of a port called foo.py. This would mean that foo.py wouldn't even get parse or loaded unless that user ask for it and ports would not need to register their own settings (making each port slightly simpler and ensuring consistency).

I think either way this change you have here is a nice simplification and cleanup up settings.js quite nicely.

[kripken]

I don't feel strongly between the approaches - your approach may be a simpler change actually.

[sbc100]

I think we could do both maybe? This approach for the current set.. and the USE_PORT for any new ones we add?

[sbc100]

Actually I think I do like my idea better and maybe this PR just makes this more complicated for the existing ports?

[kripken]

@sbc100 your idea sounds better to me too, yeah, it's nice to avoid having to do any work for a port unless it's actually used.

I'll close this then.