mk_config: Add support for Listen config directives.
mk_utils: Remove port from pidfile name.
mk_server: Support multiple listen sockets in mk_server_loop().
monkey: Arguments of mk_server_loop() changed.

Remove --port flag since it's not applicable.
Remove startup message about listening port.
en/mconf: Add Listen directive to default config.
cheetah: Fixup for removed server_config members.
logger: Fixup for removed server_config members.