Use the same parameters of dummy asyncore like in
python documentation
Switch from select to pool in asyncore.loop

By default asyncore.loop() uses select() and this has some
downsides. Biggest one is a hard fd limit of 1024. When running
bigger apps using waitress there's quite big chance of hitting that.
Using pool() instead of select() removes the limit of 1024 fd.
select() and poll() provide basically the same functionality.