Misc op5 fixes

This is a bit of a mixed bag of commits.

The first half are proper bug fixes that I've ported from op5's patchqueue for nagios ( http://git.op5.org/gitweb?p=monitor%2Fnagios.git;a=shortlog;h=HEAD )

The latter half were written while packaging naemon core. They are there to "make more things more standard".
This would make it possible to do circular inclusions, which would end up with a growing stack = crash without notice.

Just a note, and I like this patch. I just think we should add an open issue on this when this patch is accepted, so we can Patch It Later(TM)