* refactor: make tr_peerIo a class
No behavioral changes.
Use `new` and `delete` and change `struct` references to `class`.
* refactor: make some tr_peerIo fields const
* refactor: reorganize tr_peerIo fields to remove padding holes
* refactor: remove redundant field tr_peerIo.isIncoming
* refactor: make tr_peerIo.inbuf, .outbuf fields const*
Port libtransmission to C++. This PR doesn't refactor everything to c++.
Its code changes are only what was necessary to compile and link as c++.
See libtransmission/README.md for details on how to submit modernization
patches!
Co-authored-by: Mike Gelfand <mikedld@mikedld.com>