inc/aio.hpp: Changed response types.
inc/aio.hpp: Changed response types.

  io_response() is a response from a normal read or
    from a write that didn't write as much data as
    could have been possible.
  nil_response() is a response from a normal (full)
    write or from a read at end-of-file.

AmkG/hl,AmkG/hl,AmkG/hl