Connection currently is in Messaging, with a few references to it from Semantics.

As per #335, we want to make Semantics as independent from Messaging as possible.

We've talked about two approaches:

1. I've advocated keeping Connection limited to Messaging, with appropriate (but non-normative) references in Semantics. See 32d7e51 for what this would look like.

2. AIUI @royfielding wants to make a normative requirement on all versions of HTTP to process Connection. This could mean just leaving the text as it is, or moving more of Connection into Semantics (although I imagine that the bits about connection options would probably stay).

Whatever we do will need to be reconciled with this HTTP/2 text.