Make `connect` retry up to 5 times.
Faster, unsafe copy of decoded packet payload.
Unsafe copy into buffer.
Merge branch 'performance'
Take note of current window size.
Respect the remote window size.
Merge branch 'window'
Revert functional-style wnd_size to mutating version.
Explicitly reduce timer in test.

For faster testing.
Fix extension writing in `to_bytes`.
Move debug output to correct location.