Making EPERM friendlier

It would be an error (heh) to not mention libexplain in this conversation - http://libexplain.sourceforge.net/. Peter has done a huge amount of work in trying to back-track why problems have occurred and explain the problem intelligibly to the user.

I don't think this is the basis of any in-Kernel expanded messaging, but I do think that the knowledge that Peter has picked up and put in libexplain of why things go wrong and what various codes mean is a useful reference when trying to build a system that improves on the current error reporting.

Hope this helps,

Paul