* command.[ch], vty.c: cmd_execute_command() function must not attempt

	* command.[ch], vty.c: cmd_execute_command() function must not attempt
	  to walk up in the node tree if called from vtysh. Different daemons
	  might have commands with same syntax in different nodes (for example
	  "router-id x.x.x.x" commands in zebra/ospfd/ospf6d daemons).

	* vtysh.c: Reflect changes in lib. cmd_execute_command() should know
	  now that it's called from vtysh and must not attempt to walk up in
	  the node tree.

	[pullup candidate]