lnd: add litecoin support for Neutrino

[ghost]

Please could you review the following proposal for enabling litecoin support in LND/Neutrino :

LND/config.go :
allow the configuration of litecoin.node=neutrino

LND/chainparams.go/applyLitecoinParams :
apply some litecoin chainparams settings that were missed in the original implementation, namely:
GenesisBlock information
PowLimitBits and PowLimit

Ref: lightninglabs/neutrino#142

[wakiyamap]

Isn't it better to copy DNSseed too?

	dnsSeeds := make([]chaincfg.DNSSeed, len(litecoinParams.DNSSeeds))
	for i := 0; i < len(litecoinParams.DNSSeeds); i++ {
		dnsSeeds[i] = chaincfg.DNSSeed{
			Host:         litecoinParams.DNSSeeds[i].Host,
			HasFiltering: litecoinParams.DNSSeeds[i].HasFiltering,
		}
	}
	params.DNSSeeds = dnsSeeds

[ghost]

@wakiyamap yes, in general it would be best if the entire litecoinParams is copied over, but I don't know a way to do that without copying each data element explicitly. By the way, LND uses its own seeding as defined in lnd/chainregistry.go (line 561 - 595)

[wakiyamap]

@Wowee0 thanks reply!
lnd/chainregistry.go (line 561 - 595) is dnsseed of layer2(lnd).
Dnsseed of layer1 is different.

So I think this would load the default BTCtestnet dnsseed.

[ghost]

@wakiyamap ok, yes your code above should indeed be included - done. Good find!

[Roasbeef]

Closing due to inactivity.