// create file called "X.[messageid].msg" located in the store
// the contents of the file is the bytes of the message
// if a message with m's message id already exists, it will
// be overwritten
// X will be 'i' for inbound messages, and O for outbound messages
func write(store, key string, m packets.ControlPacket) {
filepath := fullpath(store, key)
f, err := os.Create(filepath)
chkerr(err)
werr := m.Write(f)
chkerr(werr)
cerr := f.Close()
chkerr(cerr)
}
