This commit adds the new litecoin testnet4 parameters to the set of
currently supported RPC parameters. Due to the way golfing handles
namespacing we had to implement a bit of a hack in order to allow both
litecoin and bitcoin parameters to be used within the codebase. In the
future, we may create a structure similar to chaincfg.Params _directly_
within lnd so the implementation can be a bit cleaner.
With this commit, support for changing the target network (testnet,
simnet, etc) has been finalized. Previously a command line option was
present to swap networks, but the RPC port wouldn’t automatically be
updated to reflect the network.