LOGGING: configure logging from the vty

We can now configure logging to (multiple) files, stderr and syslog
from the vty command line in a persistent way (config file)
diff --git a/include/osmocom/vty/command.h b/include/osmocom/vty/command.h
index 69e9e77..caf0414 100644
--- a/include/osmocom/vty/command.h
+++ b/include/osmocom/vty/command.h
@@ -70,6 +70,7 @@
 	CONFIG_NODE,		/* Config node. Default mode of config file. */
 	SERVICE_NODE,		/* Service node. */
 	DEBUG_NODE,		/* Debug node. */
+	CFG_LOG_NODE,		/* Configure the logging */
 
 	VTY_NODE,		/* Vty node. */