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/doc/babeld.texi b/doc/babeld.texi
index b6eeced..8f67197 100644
--- a/doc/babeld.texi
+++ b/doc/babeld.texi
@@ -109,7 +109,7 @@
 @deffn {Command} {show babel database} {}
 @deffnx {Command} {show babel interface} {}
 @deffnx {Command} {show babel neighbour} {}
-@deffnx {Command} {show babel running-config} {}
+@deffnx {Command} {show babel parameters} {}
 These commands dump various parts of @command{babeld}'s internal
 state.  They are mostly useful for troubleshooting.
 @end deffn
@@ -117,8 +117,8 @@
 @node Babel debugging commands,  , Show Babel information, Babel
 @section Babel debugging commands
 
-@deffn {Babel Command} {debug @var{kind}} {}
-@deffnx {Babel Command} {no debug @var{kind}} {}
+@deffn {Babel Command} {debug babel @var{kind}} {}
+@deffnx {Babel Command} {no debug babel @var{kind}} {}
 Enable or disable debugging messages of a given kind.  @var{kind} can
 be one of @samp{common}, @samp{kernel}, @samp{filter}, @samp{timeout},
 @samp{interface}, @samp{route} or @samp{all}.  Note that if you have