IPv6 Support

[hgn]

Currently only IPv4 is supported. The code should be cleaned to be IPv4 and IPv6 compatible. The simplest solution is to calculate a "route" for a given router id and substitute at the end the router-id with all prefixes for IPv4/IPv6. Just calculate the route once for each router. But this will not work if a network has multiple routers (multihomed network). So this must be added and carefully tested regarding the following scenarios:

• A(prefix:10.0.0.0/24), B(prefix:10.0.0.0/16), C(prefix:10.0.0.0/8) <-- the most specific route MUST be selected.
• A(prefix:10.0.0.0/24, 11.0.0.0/24), B(prefix:10.0.0.0/16), C(prefix:10.0.0.0/8) <- similar, but multiple networks
• A(prefix:0/0), B(prefix:0/0), C(prefix:6.0.0.0/8) <-- two default gateways