Strictify implementation WRT to the RFC

[lucasdicioccio]

We should make the http2-client library adhere more strictly to the RFC when the server sends bogus frames.

This is a meta bug and we should consider whether it's fine to be strict, loose, or let users pick whether to error on things like:

• unwanted frames on idle/closed streams
• increasing IDs only
• invalid settings
• invalid window in flow-control
• invalid frame sizes
• data-consumed out of flow-control limits
• authority of push promise https://tools.ietf.org/html/draft-ietf-httpbis-http2-17#section-10.1
• ...

We should consider the performance/code readability trade-offs thoroughly on a case-by-case basis.