Subnet broadcast is not possible

[fjwbarnard]

Sending to Endpoint.broadcast() is equivalent to IPV4 255.255.255.255, but trying to send to a subnet broadcast address (e.g. 192.168.1.255 for a subnet of 255.255.255.0) using Endpoint.unicast() throws permission denied/file descriptor Socket Exceptions on Android.

Directly using RawDatagramSocket allows setting RawDatagramSocket.broadcastEnabled=true which is required for sending to a subnet broadcast address.

1. Either expose the broadcastEnabled field for the Endpoint.unicast() constructor,
2. or expose the address field for the Endpoint.broadcast() contructor.