lnd: removing activeNetParams global, passed around instead via configs

This commit removes the activeNetParams global in chainparams.go. This
is necessary to isolate code from the lnd package so we can import it
for use in tests, other projects, etc.

chainparams.go

@@ -10,10 +10,6 @@ import (
 	litecoinWire "github.com/ltcsuite/ltcd/wire"
 )
 
-// activeNetParams is a pointer to the parameters specific to the currently
-// active bitcoin network.
-var activeNetParams = bitcoinTestNetParams
-
 // bitcoinNetParams couples the p2p parameters of a network with the
 // corresponding RPC port of a daemon running on the particular network.
 type bitcoinNetParams struct {