Choose unique default Ports for dcrlnd

[karamble]

Background

DCRLND and BTC LND currently assign the same ports in the default configuration. This leads to conflicts when both DCR and BTC Lightning are running on the same machine and requires manual configuration to run both daemons in parallel.

Steps to reproduce

Run LND and DRCLND in the default configuration on the same machine. Tested with IPv4, i expect the same problem with IPv6 setups.

Expected behaviour

We should choose unique ports for the DCRLND instead of: 8080,9735,10009 for IPv4 and their respective IPv6 ports

[matheusd]

One important issue here is making sure existing nodes are still accessible. Nodes will record the address of their peers, so outright changing the port an existing node is using means other nodes will not connect to them.

[jrick]

worth noting that while technically this can affect ipv6 configurations that only have a single ip address, those situations should be exceedingly rare (I have only come across them on some poorly-misconfigured VPSs). in any normal situation, you have an /64 prefix at least, and can add more external ip addresses to the network interface then you will ever be able to use.

how much do we care about ipv4?