lnd+config: move config parsing to cmd

Now that we have access to the configuration parsing outside of the
main package, we can move the actual parsing to the command line
package.

lnd.go

@@ -150,17 +150,11 @@ type rpcListeners func() ([]*ListenerWithSignal, func(), error)
 // Main is the true entry point for lnd. This function is required since defers
 // created in the top-level scope of a main method aren't executed if os.Exit()
 // is called.
-func Main(lisCfg ListenerCfg) error {
+func Main(config *Config, lisCfg ListenerCfg) error {
 	// Hook interceptor for os signals.
 	signal.Intercept()
 
-	// Load the configuration, and parse any command line options. This
-	// function will also set up logging properly.
-	loadedConfig, err := LoadConfig()
-	if err != nil {
-		return err
-	}
-	cfg = loadedConfig
+	cfg = config
 	defer func() {
 		ltndLog.Info("Shutdown complete")
 		err := RootLogWriter.Close()