* Ensured you can add multiple callbacks for any RPC, including basic ones.

* Extra RPC:s will be called _after_ the basic ones.
  * One specific usecase is hook for `copy-config` (see [doc/ROADMAP.md] that can be implemented thus way.
* `rpc_callback_register` added a namespace parameter. Example:
   ```
     rpc_callback_register(h, empty_rpc, NULL, "urn:example:clixon", "empty");
   ```

docker/base/Makefile.in

@@ -43,7 +43,7 @@ IMG   = clixon/clixon # base image
 
 SHELL	= /bin/sh
 
-.PHONY: all clean distclean docker push depend install-include install uninstall
+.PHONY: all clean distclean docker push depend install-include install uninstall test
 
 all:	
 	echo "Run make docker to build docker image"
@@ -58,6 +58,8 @@ clean:
 distclean: clean
 	rm -f Makefile *~ .depend
 
+test:
+
 docker: clixon Dockerfile
 	sudo docker build -t $(IMG) .  # --no-cache