TODO 2.1

- support in core for unix sockets
fury-httpd: multiplex connections to local fastcgi server

- write buffers immediate write optimization
low hanging fruit for better overall performance

- option to deactivate a listener without closing its listening socket
fury-httpd: allow for a hybrid prefork/multiplexed server process model

- stream write buffers
makes things a lot simpler for some cases, and we may also be able to use
stream_copy_to_stream() which should give a small performance boost

TODO 2.2

- alternative backend based on libevent
better performance than current select() backend under high load, should be
implemented as a build-time option

- support for accept mutex (sysv sem/shm maybe)
avoid the "thundering herd" effect with kernels that wake up all listening
processes when there's an incoming connection