[MEDIUM] got rid of event_{cli,srv}_write() in favor of stream_sock_write()

[MEDIUM] got rid of event_{cli,srv}_write() in favor of stream_sock_write()

The timeouts, expiration timers and results are now stored in the buffers.
The timers will have to change a bit to become more flexible, and when the
I/O completion functions will be written, the connect_complete() will have
to be extracted from the write() function.