Simplify stream priority.
reinstitute per-DATA compression
fix broken xrefs
move error text from setting to flag
Editorial tweak to last
Adding implementation note.
Adding tree+weight prioritization change.
Adding change log entry.
Merge branch '445-gzip' of git://github.com/phluid61/http2-spec into gzip-te

Conflicts:
	draft-ietf-httpbis-http2.xml

Added security considerations.
Added note about Content-Length.
Fixing bad 1952 cross reference.
Priority edits.  Closes #464.
Closes #469
Altering stream priority description, introduces 'parent' terminology.  For #465.
Attempting to making dcsommer happier.
Merge branch 'master' of https://github.com/http2/http2-spec