Replace `close()` by `CLOSE()`
Now a support of EINTR when `close()` returns -1.
Now uses `fork()` !
Requests handling is not sequential anymore.
Damn this is good.
Replace `BACKLOG` by `SOMAXCONN`
Neat implementation of `output()`
The amount of data sent/written is now checked.

I use a `do/while` loop instead of a `for` one because it looks cleaner.