Print ALTSVC when received (but not processed).
Fix ALTSVC test for h2-13
Fix indentation
Fix PONG and its test
Fix connection tests so that actually send HPACK-compressed headers
Fix table size computation
Priority parameters are sent out on HEADERS and PRIORITY.

Priority-based stream transmission is not implemented yet.
Pass creation options to Connection.new
Merge branch 'stream-h2-13-wip' into draft-13
Merge branch 'hpack-08-wip' into draft-13
Merge branch 'draft-13' into profile-coverage-h2-13