* refactor: include <memory> when using shared_ptr or unique_ptr
* refactor: include <cstdio> iff we use it
* refactor: include <cstring> iff we use it
* refactor: include <cstdlib> iff we use it
* refactor: include <string_view> or <string> iff we use it
* refactor: include <array> iff we use it
* refactor: include <ctime> iff we use it
* refactor: include <cctype> iff we use it
* refactor: misc #include cleanups in libtransmission
* refactor: move handshake_done args into a convenience struct
* refactor: move peer_id from peerIo to tr_handshake
tr_handshake is a short-term object and tr_peerIo is long-term, so this
effectively narrows the scope of this field.
* chore: remove unused field tr_peerIo.isEncrypted
* refactor: add tr_peer_id_t type to hold peer ids.
this is a 'using' alias to a std::array<> so that code passing peer-ids
around doesn't have to memcmp / memcpy PEER_ID_LEN anymore. Also removes
the now-unused PEER_ID_LEN macro.
