Refactor the netmgr API to use iov
The native libuv uses iov, and we lose that ability in our own API. Restore the iov, so it can be used f.e. in TCPDNS and other places instead of copying memory back and forth.
The native libuv uses iov, and we lose that ability in our own API. Restore the iov, so it can be used f.e. in TCPDNS and other places instead of copying memory back and forth.