Update to h2-16, hpack-10

Closes #1179

Note that there are no hpack tests for draft 10, yet. I left the test version at 9, since there is no implementation change.
Note that http2 spec didn't (yet) rename the setting `HEADER_TABLE_SIZE` to `DYNAMIC_TABLE_SIZE`. It used to be the case that static headers were copied into the same table with dynamic ones. That's no longer the case, which is why in hpack, this parameter is scoped to the dynamic table size.