(svn r5330) -Backport: r5292, r5293, r5295, r5297
-Fix: When using SIOCGIFCONF to detect network interfaces accomodate for the fact that struct sockaddr doesn't have fixed size in all implementations
-Fix: Not all network interfaces are capable of broadcasting. Don't record those which aren't
-Fix: Not all networks are /24. Generate proper broadcast addresses for non-/24 nets