[SKOS] Material for ISSUE-48 and ISSUE-77

Hi,

I have gather some material for the discussion on whether to include 
indexing properties (and if yes, which one) in SKOS.
http://www.w3.org/2006/07/SWD/wiki/SkosDesign/Indexing

It is mostly derived from a big discussion we had some weeks ago on the 
SKOS list.

It's a three page read, and quite late. But I hope it's an easy read, 
and think it is relevant, because this is an issue we've not discussed a 
lot during our own telecons...

Cheers,

Antoine