Have a `munin-check` to handle configuration check

[snide]

It would be nice to have a file that checks the validity of the various config files: munin.conf, munin-node.conf like apachectl or perl -C does.

An option to show the parsed config would ease debugging why a graph doesn't show up (Looking into a huge pile of debug log doesn't qualify as easy)

It should also take into account the remotely-discovered plugins.

Thx Tarjei for the idea.