fix: handle edge cases in frame read and write

[sabify]

This PR handles edge cases on AsyncRead and AsyncWrite methods when ready! macro may return early that may cause losing to track the data based on the defined protocol. Also this PR fixes the buffer issue when used in a stack like kaminari library.

Related: zephyrchien/kaminari#7 and zephyrchien/kaminari#8.

[zephyrchien]

Thanks a lot for this PR.

The current impl works this way:

1. read to buf;  if not enough then: copy buf to vec
2. copy vec to buf

Personally I prefer to twist it to this way, like a buffered reader:

1. always read to vec
2. if enough then: copy vec to buf

===
Apologies for the delayed response.

[sabify]

Please check out the #2 PR.