Proposed text for #458
Adding ability to send PRIORITY on closed stream, as new priority scheme demands.
Removing Alt-Svc restrictions on intermediaries.  Closes #462
Clarifying requirements on ALPN use
Merge pull request #475 from dcsommer/master

Proposed text for #458
Merge pull request #489 from http2/issue468

Adding ability to send PRIORITY on closed stream (Closes #468)
Removing BLOCKED
Merge pull request #504 from http2/noblocked

Removing BLOCKED.  Closes #500
Closes #484
Moving ALTSVC frame to alt-svc doc
Moving alt-svc to informative
Noting conditions on TLS usage
add title to RFC6585 reference
Noting exception
Merge branch 'master' of https://github.com/http2/http2-spec
Merge pull request #507 from http2/extendaltsvc

Make ALTSVC an extension.  Closes #499.
Restricting to AEAD modes only.
Updates from discussion
Fixing references
Fixing bad xref