length_delimited refactoring

[kpp]

There is some work to be done to make the code for tokio_io::length_delimited a little bit cleaner. We need to get rid of custom Framed* types in favour of tokio_codec::Framed* types, rename length_delimited::Decoder -> Codec. Also the logic of length_delimited::Framed needs to be moved into Codec.

TODO list:

• implement Codec (Refactor codec::length_delimited #575)
• remove Framed* (Refactor codec::length_delimited #575)
• move to tokio_utils tokio (Move tokio_io::codec::length_delimited module to tokio::codec #568)
• mark old length_delimited as depricated (Move tokio_io::codec::length_delimited module to tokio::codec #568)
• tests for Potential non-terminating loop in tokio_io::length_delimited::FramedWrite #497 (Fix non-terminating loop in tokio_io::length_delimited::FramedWrite #576)
• fix Potential non-terminating loop in tokio_io::length_delimited::FramedWrite #497 (Fix non-terminating loop in tokio_io::length_delimited::FramedWrite #576)

[carllerche]

I would move length_delimited into tokio_utils.

[hawkw]

The

• move to tokio_utils tokio
• mark old length_delimited as deprecated

parts of this ticket were finished in #568. I'm working on the remaining tasks.

[kpp]

Thanks Eliza

[kpp]

Good job Eliza!

[hawkw]

My pleasure!