Send UDP broadcast packets

[fdammeke]

This allows one to use the in-car entertainment system or any other WIFI network
ip neigh show doesn't display hosts when connected to external WIFI

[olivluca]

Just a couple of quiestions (since I'm not using AAStarter/AAGateway anymore I cannot test by myself):

1. if the broadcast works there should be no need to issue the "ip neigh" command and loop through the returned addresses, just send the broadcast and be done with it, right? (at least for the "listening" case).
2. shouldn't you use two broadcasts (one for ipv4 and the other for ipv6)? (or just one, depending on the setting of ignoreipv6) (or maybe 255.255.255.255. does both and then ignoreipv6 is not needed).

[fdammeke]

I think the code could be tweaked a bit more indeed.

From my point of view the broadcast solution only works for ipv4, there is no broadcast mechanism in ipv6 (ref: http://www.tcpipguide.com/index.htm), so I think both mechanisms should co-exist.

I'll update the PR based on your remarks.

I'm testing the code with a Nexus 4 connected to Android Studio Desktop Head Unit 2.0

[olivluca]

I don't remember the exact details, but I added the "use ipv4/use ipv6" mode because both phones had both protocols and the timing difference made the whole setup not work (my in car radio is extremely finicky).
Maybe it's not needed in listening mode and you can just use ipv4.