babeld: justify "running-config" meaning in CLI

The primary focus of this commit is to make "show running-config"
command display more current configuration, including some of the bits
previously seen in the output of "show babel running-config". Besides
that, the following commands were renamed for consistency with the
syntax of other components:

"debug *" to "debug babel *" (and moved to top level)
"show babel running-config" to "show babel parameters"

* babel_interface.c
  * show_babel_running_config(): rename to show_babel_parameters(),
    update syntax pattern, don't call show_babeld_configuration()
  * babel_if_init(): update respectively
  * babel_enable_if_config_write(): new VTY helper for static
    babel_enable_if
* babel_interface.h: add extern declaration
* babel_main.c: unset all debug options by default
  * show_babel_main_configuration(): remove debug options decoder
* babel_zebra.c
  * babel_debug(): rename to debug_babel(), update syntax pattern
  * no_babel_debug(): rename to no_debug_babel(), update syntax pattern
  * babelz_zebra_init(): update respectively
  * debug_babel_config_write() new VTY helper for static debug_type
* babel_zebra.h: add extern declaration
* babeld.c
  * babel_config_write(): add the code to output "debug babel *",
    "router babel", "redistribute *" and "network *" statements
  * show_babeld_configuration(): dismiss
* babeld.h: remove extern declaration
* babeld.texi: update for renamed commands
* babeld.conf.sample: idem, add debug statements block
diff --git a/babeld/babel_main.c b/babeld/babel_main.c
index 4cb2d83..3d83091 100644
--- a/babeld/babel_main.c
+++ b/babeld/babel_main.c
@@ -77,7 +77,7 @@
 struct timeval babel_now;         /* current time             */
 
 unsigned char myid[8];            /* unique id (mac address of an interface) */
-int debug = BABEL_DEBUG_COMMON;
+int debug = 0;
 
 int default_wireless_hello_interval = -1;
 int default_wired_hello_interval = -1;
@@ -523,30 +523,6 @@
 void
 show_babel_main_configuration (struct vty *vty)
 {
-#ifdef NO_DEBUG
-    vty_out(vty, "No debug.%s", VTY_NEWLINE);
-#else
-    vty_out(vty, "Activated debug options:");
-    if (debug == BABEL_DEBUG_ALL) {
-        vty_out(vty, " all%s", VTY_NEWLINE);
-    } else {
-        vty_out(vty, "%s%s%s%s%s%s%s%s%s%s%s%s%s",
-                debug & BABEL_DEBUG_COMMON  ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_COMMON  ? "    common"   : "",
-                debug & BABEL_DEBUG_KERNEL  ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_KERNEL  ? "    kernel"   : "",
-                debug & BABEL_DEBUG_FILTER  ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_FILTER  ? "    filter"   : "",
-                debug & BABEL_DEBUG_TIMEOUT ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_TIMEOUT ? "    timeout"  : "",
-                debug & BABEL_DEBUG_IF      ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_IF      ? "    interface": "",
-                debug & BABEL_DEBUG_ROUTE   ? VTY_NEWLINE    : "",
-                debug & BABEL_DEBUG_ROUTE   ? "    route"    : "",
-                VTY_NEWLINE);
-    }
-#endif
-
     vty_out(vty,
             "pid file                = %s%s"
             "state file              = %s%s"