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.

cmd/lnd/main.go

@@ -9,12 +9,20 @@ import (
 )
 
 func main() {
+	// Load the configuration, and parse any command line options. This
+	// function will also set up logging properly.
+	loadedConfig, err := lnd.LoadConfig()
+	if err != nil {
+		_, _ = fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
 	// Call the "real" main in a nested manner so the defers will properly
 	// be executed in the case of a graceful shutdown.
-	if err := lnd.Main(lnd.ListenerCfg{}); err != nil {
+	if err := lnd.Main(loadedConfig, lnd.ListenerCfg{}); err != nil {
 		if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
 		} else {
-			fmt.Fprintln(os.Stderr, err)
+			_, _ = fmt.Fprintln(os.Stderr, err)
 		}
 		os.Exit(1)
 	}