Added Server class and keep the old struct of threads as it was

This should be fixed in next patches.
Remove useless includes of server.c
It seems to work without this function...
Thread of receveis messages kill itself in the end of the loop
Remove array of pthreads, and introduce client_fds unordered_set to hold client's fd
Remove CFLAGS and enable the verbose flag
DIE, MAX_CONN, DIE

Now we can have a lot of connections. After this we maybe have to clean all fds that are not used anymore.